450 Single Honda vs. Yamaha

[civicsit]

We are currently looking at a new engine, and at the top of our list is a 450 single. More spec. Honda or Yamaha. The engines are very similar except for just a few differences. The Honda is a unicam and the Yamaha is a DOHC. The main difference that we are concerned with though is that the Honda is a wet sump and the Yamaha is a dry sump. We are wondering if anyone has heard of or has had problems with the Honda oil starving because of sustained g-forces because of the wet sump.

We have noticed that quite a few teams have used the Yamaha, but not very many teams have used the Honda. We are hoping that we are not missing anything, so that is why we are asking about known problems.

Also, if you have run a 450 single in the past or now, why did you choose the one that you did?

Any information would really help, and may prevent us from making a big mistake.

Thank you

[civicsit]

We are currently looking at a new engine, and at the top of our list is a 450 single. More spec. Honda or Yamaha. The engines are very similar except for just a few differences. The Honda is a unicam and the Yamaha is a DOHC. The main difference that we are concerned with though is that the Honda is a wet sump and the Yamaha is a dry sump. We are wondering if anyone has heard of or has had problems with the Honda oil starving because of sustained g-forces because of the wet sump.

We have noticed that quite a few teams have used the Yamaha, but not very many teams have used the Honda. We are hoping that we are not missing anything, so that is why we are asking about known problems.

Also, if you have run a 450 single in the past or now, why did you choose the one that you did?

Any information would really help, and may prevent us from making a big mistake.

Thank you

[Grant Mahler]

We are running the Suzuki, because both the Honda and the Yamaha are/were carbeureted and the Suzuki is already FI. Also, it has a dry sump.

[civicsit]

We can't run a Suzuki/Kawasaki because of an availability issue.

[Steve O]

We use the yamaha since its cheaper and easier to come by. We like it.

Just remember wr450=449cc yfz450=is 449cc on the '06 and newer but 439cc otherwise.

Steve

[LU-Bolton]

We started running the Yamaha WR426 back in '04, WR450 since then. It was the most commonly available one at that time. Because of extensive knowledge of the WR and our good repore with yamaha, we have continued to use it.

Aaron Cassebeer

[exbaja]

I work in the motocross industry. The yahama is a good engine, though it is older in design, larger, and externally dry sumped. It is a 5 valve engine, but do not let that sway you into thinking it is better, because the 4 valve engines can make as much if not more power because their ports are more efficient. All modern motocross 4 strokes are factory dry sumped. The honda is a very very compact engine. It leaves a little to be desired in the tuning dept because of the single camshaft. Overlap is built into the cam. It does use a roller follower for the exhaust which allows extremely high exhaust valve opening and closing geometries. All other motocross 4 stroke engines from japan are direct action on a bucket. I believe the yamaha also still uses a counter balancer which makes the engine larger and heavier. Honda may also.

The honda engine is dry sumped with a wet sump transmission. It uses two separate oil systems. A dedicated clutch/tranny oiling system and a engine oil system.

The Suzuki EFI engine has nothing special about it that is different from a carbureted engine. The new 08 450 engine is very very compact and light, and has a very efficient intake port.

The suzuki has a unique gravity and pressure scavenged crankcase. Crankcase pressure along with gravity pull oil out of the bottom of the crankcase past a one way reed valve into the left half of the case where the sump pump is.

Not really familiar with Kawasaki engines other than they are DOHC 4 valve dry sump engines. None of the motocross engines are electric start, you must go to the off road versions of the engines to get E start that FSAE requires. Most E start engines are relatively new, and therefore will be around 1k each.

Again, all motocross/off road high performance 4 stroke engines are dry sumped. All but yamaha do it internally using the transmission as an oil tank.

All of these engines are very reliable...when built correctly. Keep a close eye on the valves, have the seats cut by an experienced person on a SERDI valve machine, and do not lap the valves! They are Ti and coated. Lapping takes the coating off and they will go south in short order.

[Big Bird]

Greetings all,

A few random thoughts on the topic. We've run a WR450 for a few years now, and are good friends with the Tokyo Denki guys who have been running a Honda CR450 for a bit longer. I'm not convinced one is significantly more suited for FSAE than the other.

Firstly, exbaja has made some very good points, particularly about number of valves. As engineers we need to look past gimmicks used for marketing. 4 and 5 valve both work. Other issues have a much greater bearing.

We chose brand Y because we have a good working relationship with the company, and they were the first Japanese manufacturer to offer electric start on one of their competition 450's. I know the TDU guys had a lot of trouble in their first couple of years trying to retrofit an electric start to a kickstart Honda 450. They learnt a lot, but it was a long road for them.

The Yamaha has been damn reliable for us, spared a few issues we had when the engine team decided they needed to compensate for the reduced capacity by playing around internally (mainly high comp pistons). Don't go stuffing around internally, you can get them to run perfectly fine with a well refined engine management program.

The Honda had some starter motor issues with their earlier models, but I believe things are better now.

I doubt either engine has a definitive advantage performance wise, and if you are sweating over which engine is better in terms of output then you've missed the point with a 450 in the first place. Our primary decision was to reduce size and complexity, based on the belief that engine performance is not critical in this application. You make greater gains by completing the project on time and testing comprehensively. So if you follow that philosophy, choosing between Honda/Yam/Suz/KTM 450's is an academic argument.

I can't speak for oiling issues, other than we have built our own oil tank and used the original Yamaha pumping system, and never had any worries.

If you are thinking 450 single, then put in place a management plan for the introduction of this philosophy. FYI, our plan was roughly:
First year, 200kg car, 50hp engine
Second year 180kg car, 55hp engine
Third year 160kg car, around 60hp engine
We met those goals, and each of the cars were successful, (mainly because they were reliable and sorted). Set achievable goals for each project, and don't listen to any buffoon who wants to tell you that your car needs to be 140kgs straight away to be competitive.

The decision should be made on what choice represents the best support for your project. If your best chance for engine supply and good parts support is brand Q, then go with them.

FSAE is all about scavenging as many of the 1000 points you can with the 50 weeks you have available to you. (So as a rule of thumb, each week is worth 20 points). Performance wise, the choice between brands is worth in the order of magnitude of maybe a point or two, whether your teams philosophy is 450 or 600, single, twin, triple or four. So from that perspective you can see it is not worth more than a day or so worrying about the brand performance, and it is much more sensible to think in terms of the support you can gather.

Cheers, hope that helps,

[civicsit]

Thanks guys,
That was pretty much what I was looking for. Mainly hearing that a FSAE team had used the Honda, since most of them use Yamaha. We have some experienced motocross guys on our team, so I already knew that the Yamaha had 5 valves and the Honda 4, but both have almost identical stock power output.

Geoff, you really put things into perspective as well with that post. The nice thing is that we already have a plan similar to what you explained, except starting at a lower weight. Since we already have about a 180kg car with a 4cyl and a tube chassis, we know we can conservatively be below 160kg with the single. We are really looking to simplify our engine department, and also reduce the cost of parts. Our current Kawasaki is just way too expensive to rebuild any part of it.

We have more support currently for the Honda, and it seems to be a favorite currently among the team. Since support is one of our requirements, it is ahead in that respect.

By the way Geoff, what problems did you have with your single when you started to increase the compression?

If anyone knows of any problems with the oiling system of the Honda, please let me know. It's great to hear from experienced members.

[BMH]

Well from my years in Motocross racing, Yamaha is the way to go when it comes to reliability and high performance power. You cant beat the reliability of the YZ 450F engine.

[A Richards]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Bryan2007:
Yamaha is the way to go when it comes to reliability </div></BLOCKQUOTE>

This may well be true on a motocross track but FSAE is a different game all together. How many people have seen a engine fail in a sae car that isnt the result of some hack up fuel injection system, poor wiring, cooling system design, wrong assembley, etc? I think that most would spend more time chasing issues with their own add ons then stressing over the reliability of their donor engine what ever make it happens to be. Motorcross bikes are seperated by 1/10ths, SAE cars are separeted by either been on the track racing or sitting beside it broken.

Ash

[Drew Price]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exbaja:

The Suzuki EFI engine has nothing special about it that is different from a carbureted engine. The new 08 450 engine is very very compact and light, and has a very efficient intake port.

..........

Again, all motocross/off road high performance 4 stroke engines are dry sumped. All but yamaha do it internally using the transmission as an oil tank.
</div></BLOCKQUOTE>

How can you say the port and combustion chamber design, cam timing, etc. of a factory designed fuel injected engine is not different from one designed for a carb? http://fsae.com/groupee_common/emoticons/icon_confused.gif

The Suzuki also an external oil tank.

Best,
Drew

[Kirk Feldkamp]

Don't forget that there is a significant amount of work to be done in order to add all the crank/cam triggers and sensors to a non-fuel injected engine. It's not necessarily 'simple' to adapt the required hardware. As more offroad bikes (the ones with starters) go that direction, expect to see more teams move over to singles. The only already fuel-injected engines with starters that I know about right now (in the US market) come on ATVs.

-Kirk

[Scrappy]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exbaja:
None of the motocross engines are electric start, you must go to the off road versions of the engines to get E start that FSAE requires. Most E start engines are relatively new, and therefore will be around 1k each.
</div></BLOCKQUOTE>

The 07 and 08 KTM 450 SX-F are both electric start from the factory, and the SX-F is a pure motocross bike, not an off roader.

[Conor]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Scrappy:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exbaja:
None of the motocross engines are electric start, you must go to the off road versions of the engines to get E start that FSAE requires. Most E start engines are relatively new, and therefore will be around 1k each.
</div></BLOCKQUOTE>

The 07 and 08 KTM 450 SX-F are both electric start from the factory, and the SX-F is a pure motocross bike, not an off roader. </div></BLOCKQUOTE>

Our team is strongly considering the KTM 450, but all the Yamaha talk has me second guessing. There doesn't seem to be much information on the KTM engines, especially no CAD model - which is a must for intake design and packaging. I'm still trying to get my hands on a Yamaha engine model. Can anybody help me out? Opinions on the KTM engine are also highly sought.

[exbaja]

Some misinformation here-

I work with 2008 RMZ450's every day. They are unavailable to the public in every country in the world but Japan currently. It is an internally dry sumped bike, no external tank. The yamaha is the only current production mainstream MX bike with an external tank and a "true" dry sump. Not to say the suzuki, kawie, and honda are not dry sump, but they use the trans and ignition cover as the tank.

The KTM is a good engine. I believe it uses roller followers, high lift cams, and inverted radius flanks on the opening sides. Can't get opening velocities as high as the KTM on any flat follower bike because the velocity is limited by the size of the follower. The Suzuki increased follower diameter this year, so higher valve opening velocities are possible. I see this as the single biggest advantage to the KTM if you are willing to take the time to understand and design cams for the application.

The KTM does have questionable parts availability, and it is for sure more expensive to get them.

All off road versions of motocross bikes made by japanese manufacturers are very similar to the MX bikes with a few exceptions. The coil has an AC output for a rectifier/regulator, there is a factory installed e start, they have different internal gearing in both the primary reduction and the trans, and the engine components are milder (ie cams and piston). Other than that, they are pretty much the same for all intents and purposes.

Modifying one to trigger an ECU would be simple. Cut a trigger wheel on a water jet, turn down flywheel slightly, press on, weld on, and use stock VR/Hall sensor for ignition triggering. Fuel triggering shouldn't be an issue and a cam wheel is not necessary on a single with one injection event.

Port shape, cam timing, and combustion chamber shape swaying you to an EFI native engine are silly things to dwell on. You should be changing at least the ports and the cams anyhow seeing as you run a restrictor.

Again, assemble the engine correctly, use clean new parts, follow a religious valve train service schedule at the very least, and get a GOOD valve job and any MX engine will be very very reliable. You should run no more than 20 hours on a complete rotating assembly if you want the engine to remain reliable. Plan on replacing cases every 4-5 engine rebuilds as the bearing bores wear out.

That's just my opinion as a ex baja guy who happens to work on a professional motocross team every day for a living http://fsae.com/groupee_common/emoticons/icon_smile.gif .

[BMH]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by A Richards:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Bryan2007:
Yamaha is the way to go when it comes to reliability </div></BLOCKQUOTE>

This may well be true on a motocross track but FSAE is a different game all together. How many people have seen a engine fail in a sae car that isnt the result of some hack up fuel injection system, poor wiring, cooling system design, wrong assembley, etc? I think that most would spend more time chasing issues with their own add ons then stressing over the reliability of their donor engine what ever make it happens to be. Motorcross bikes are seperated by 1/10ths, SAE cars are separeted by either been on the track racing or sitting beside it broken.

Ash </div></BLOCKQUOTE>

You have a point, however I say the Yamaha 450 engine is more reliable due to it being a 5 valve set-up. Yamaha has also had WAY more experience designing 4 stroke race engines than Honda, and they have had a long standing track record of being the most reliable.


exbaja: I am also a baja guy at my uni and am a hardcore fan of Motocross. Did some racing for a few years also. You mentioned working for a motocross team. Is it as an engineer? How was this opportunity presented to you? What would you recommend someone to do if they were interested in doing the same thing? Thanks!

[exbaja]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Bryan2007:

You have a point, however I say the Yamaha 450 engine is more reliable due to it being a 5 valve set-up. Yamaha has also had WAY more experience designing 4 stroke race engines than Honda, and they have had a long standing track record of being the most reliable.


exbaja: I am also a baja guy at my uni and am a hardcore fan of Motocross. Did some racing for a few years also. You mentioned working for a motocross team. Is it as an engineer? How was this opportunity presented to you? What would you recommend someone to do if they were interested in doing the same thing? Thanks! </div></BLOCKQUOTE>

As someone who works in the industry, I will tell you that there is no one bike that is more reliable than the rest in the short term, but if you do not maintain them, the yamaha *can* be more reliable in the intake valve dept because the valves are a little smaller. Do I think this is worth noting, hell no. The only folks that have problems with new 4 strokes are folks who completely abuse them and do not maintain them.

I do believe that with an aggressive camshaft profile that will work well with a restricted setup you will need to change valvetrain parts on a very regular basis...but such is a price for great performance. Opening and closing accelerations can be much higher than stock and parts will live...for a finite time. The valvetrain is really the main reliability weakness in a small high speed 4 stroke. Combine higher accelerations with short or no lash ramps and you really beat up the seat and springs.

The only advantage FSAE has for this is that I doubt you can really spin high speeds and make power given the intake restriction. Lower peak engine speeds obviously give you the ability to theoretically run something more aggressive acceleration wise than can be run on one of our race bikes.

Do I recommend working on a team? Depends on the team. Not sure what other teams are like, but on my team I am the one and only engineer. I am the engineering dept and as a new graduate, this is scary. It is a big learning curve, lots of research, asking questions to folks outside of the team and I do a lot of sitting around staring at things trying to figure them out.

I made the opportunity. Best advice I can give is network well, don't ever burn bridges and never ever be afraid to ask no matter how absurd the possibility of a position on a team seems.

[Kyle Roggenkamp]

We are running the KTM 525. It comes with electric start from the factory and puts down impressive numbers. Plus big bores are available for it. Have you looked into them at all?

[Conor]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kyle Roggenkamp:
We are running the KTM 525. It comes with electric start from the factory and puts down impressive numbers. Plus big bores are available for it. Have you looked into them at all? </div></BLOCKQUOTE>

Kyle,

How did you get the KTM in a crate? How much did it cost, who did you contact?

[VFR750R]

[/QUOTE]

You have a point, however I say the Yamaha 450 engine is more reliable due to it being a 5 valve set-up. Yamaha has also had WAY more experience designing 4 stroke race engines than Honda, and they have had a long standing track record of being the most reliable.


[/QUOTE]

hahahhhhhahhhhahaahhaaahaha
Someone needs a history lesson.
And how is 5 valves more intrinsically reliable then 4?
I have heard the seats are harder in the Yamahas and so they need less frequent valve adjustments, but i guess the newest ones 06-newer? are equal to the yamahas

[BMH]

Well I have had a YZ-F 400, 426, and 2 450Fs (04 and 06) and Have hardly had any problems with any of them. The honda on the other hand requires very frequent maintenance, and have had problems with the 02-04 model years. I speak from experience with them.

[VFR750R]

That matches up with what I've heard on the yamaha singles but i couldn't let the blanket 4 stroke racing experience comment go.

Too be honest, i've been disappointed by Honda's CRF service intervals. It's hard to see why they took the path they did on the CRF450. I heard valve adjustment intervals on the CRF250 of only 5 hours. For those dealing with these motors a company called Brush Wellman makes some material for replacement guides and seats that are wayyyyy better.

http://www.brushwellman.com/alloy/tech_lit/case%20history%20pr2%20racing.pdf

[Kyle Roggenkamp]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Conor:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kyle Roggenkamp:
We are running the KTM 525. It comes with electric start from the factory and puts down impressive numbers. Plus big bores are available for it. Have you looked into them at all? </div></BLOCKQUOTE>

Kyle,

How did you get the KTM in a crate? How much did it cost, who did you contact? </div></BLOCKQUOTE>

We got the KTM motor from Polaris. They donated it to us, so I'm not sure on cost, but they aren't cheap.

[Big Bird]

Karl,

Sorry to take a while to get back. In answer to your question, a couple of years back the lads fitted a non OEM high-comp piston, which after probably a bit too much work dropped its skirt and cocked sideways in the bore - resulting in a big hole poked in the side of the barrel.

Prior to that we had run for two seasons (4 comps and lots of testing) with stock standard internals, and never had any engine troubles at all. Whats more, the early unmodded engines were a lot smoother and a lot more driveable.

Keep them standard, spend a good bit of time refining a map for transient behaviour, and you'll have a nice driveable little engine.

[Storbeck]

Question for RMIT I've seen many mentions of having not changed anything internally.

Not 100% sure on this but it seems that the main difference between the YZ and WR internally is the cams. Piston, ports, valve sizes pretty much everything else the same. Older bikes had the same cams between the two models with only a timing change, newer bikes have completely different cams between YZ/WR. I would be surprised to hear that you guys didn't at least substitute YZ cams, or if you were using an older engine change the timing to YZ spec.

Is it true that you guys don't do this? You run the WR completely 100% stock internally?

Not involved in FSAE any more, but I happen to have an 07 WR450 myself and am currently debating between 06,07,08 YZ or aftermarket cams to install in the bike. Of course it has no relevence to the bike since everything else is different just curious what you guys did.

[Gerben van der Lei]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Big Bird:
Karl,

Sorry to take a while to get back. In answer to your question, a couple of years back the lads fitted a non OEM high-comp piston, which after probably a bit too much work dropped its skirt and cocked sideways in the bore - resulting in a big hole poked in the side of the barrel.

Prior to that we had run for two seasons (4 comps and lots of testing) with stock standard internals, and never had any engine troubles at all. Whats more, the early unmodded engines were a lot smoother and a lot more driveable.

Keep them standard, spend a good bit of time refining a map for transient behaviour, and you'll have a nice driveable little engine. </div></BLOCKQUOTE>

Hi,

This pretty much agrees with my experience. We ran the WR last year with a big bore + different cams. It gave 55 hp @ the gearbox but it lasts for about 10 hrs. Since we are building a weekend racer car that is not an option. After the UK event we changed back to stock internals while keeping the cams. [basically pretty much the YZ cams] while giving a bit less horsepower [50 hp @ the gearbox] it was better to drive. These figures are enough to be just about the fastest car on the track.

I am curious though what our new spec engine will do at the track http://fsae.com/groupee_common/emoticons/icon_smile.gif