RD350 vs RD350 YPVS

[stuntmonkee]

Looking at Mito conversions again (as it doesn't want sell).

YPVS engine is what I'd like but there a bit thin on the ground. What would a RD350 (non-powervalve) be like, is there much difference:

a. power wise

b. in the mounting points (want to use the mito350.tk mounts)

c. could you turn one into a YPVS engine with barrels etc?

Asking to hopefully widen my search and there's a tuned RD on ebay at the moment (bit expensive though and probably a grenade)

Cheers

[cagimaha]

I've got an RD350LC motor in my mito using the mito350.tk mounts, the crankcase mounting points are the same so it bolts right up no bother.

You can't fit the later powervalve barrels to the LC cases as the stud pattern is different. The LC cases do have several advantages though, they can be modded to run reverse cylinder easily, TZ250/350/700/750 top ends drop straight on (a standard TZ350 is good for 160mph so they're not lacking in power). There is a pretty big difference in power between the LC and the powervalve as standard though. A good standard LC is around 45bhp maybe and a PV might be knocking out 60 or so. They're both easily tuned, I've got some KR1S carbs (go straight into the original intake rubbers), opened out reed blocks, skimmed head, ported barrels and some Swarbrick pipes and it goes well enough.

If you need more than 65bhp reliably then you're better off going for a PV motor really. Porting, sorted squish, big carbs, pipes and some TDR250 or CR250 reed blocks will give a reliable 80ish bhp. More than that and you need to be looking at the big bore route a la Greengoatchoker. You can get big power and keep it reliable, depends how deep your wallet is! Any other questions, don't hesitate to ask. Cheers, Ben

[stuntmonkee]

Sounds like a powervalve is more appropriate for me then...

...Cheers !

[wazrs257]

Glad to hear you haven't abandoned the project

If you need more than 65bhp reliably then you're better off going for a PV motor really.

Agree with you there Ben. Having said that, the Len Manchester F2 LC's were putting out almost TZ power back in the day. So the LC motor can deliver the goods as long as you're prepared to keep on top of the engine rebuilds. Probably not practical for the road though!

[stuntmonkee]

Think this with Renthal Fatbars and maybe a smaller seat unit

[wazrs257]

Think this with Renthal Fatbars and maybe a smaller seat unit

Would look great with a reverse barrel LC motor.

To be honest, you dont need massive amounts of power in a chassis this small. My Aprilia puts out 55-60 bhp, weighs about 110kg with a full tank, and is brilliant fun on the right roads.

[stuntmonkee]

YPVS engine just surfaced on the bay.

Just off to send an email...

[chris675]

any info on how to make a reverse seizure? would love one in a aprilia rs 250!

[wazrs257]

any info on how to make a reverse seizure? would love one in a aprilia rs 250!

I've only done this with a FS1-E, but it should be simple enough to achieve on an LC (Not so a YPVS). It should be just a case of turning the barrels and pistons round, the head would need to stay the normal way because of the water pipe that runs up behind the back of the barrels to the head. Providing that there is sufficient room to fit the carbs in front of the engine with some kind of 'stone guard', you should be laughing.

Whether or not the engine will be better with the barrels reversed is a matter for debate. Alot of manufacturers have tried it, Suzuki & Rotax have even hedged their bets by fitting a combination of forward and reverse barrels!

[cagimaha]

Reverse cylinder on an LC is pretty easy, to get decent performance out of it you have to do a little work on the transfer mouths in the crankcases because they are now flowing in the opposite direction if you know what I mean. The main problem is packaging the exhausts cos the mito frame has a big cross spar that hangs right where the pipes want to be and you need a fair bit of length to get decent performance. Check a TZR250 3MA out and you'll see what I mean, Yamaha had to cross the pipes over to give them a long enough run and they still ended up with mega short silencers. There is a mito out there with a reverse cylinder YPVS engine somewhere but it's had some major surgery, the back of the crankcases has been chopped off and welded up to allow the engine to be moved further back to allow the carbs to fit in front, this has got rid of the kickstart so it's bump only. Here is a pic of it:

http://maurord.altervista.org/_altervista_ht/mitofinita1.jpg

[spacemonkey]

Reverse cylinder on an LC is pretty easy, to get decent performance out of it you have to do a little work on the transfer mouths in the crankcases because they are now flowing in the opposite direction if you know what I mean. The main problem is packaging the exhausts cos the mito frame has a big cross spar that hangs right where the pipes want to be and you need a fair bit of length to get decent performance. Check a TZR250 3MA out and you'll see what I mean, Yamaha had to cross the pipes over to give them a long enough run and they still ended up with mega short silencers. There is a mito out there with a reverse cylinder YPVS engine somewhere but it's had some major surgery, the back of the crankcases has been chopped off and welded up to allow the engine to be moved further back to allow the carbs to fit in front, this has got rid of the kickstart so it's bump only. Here is a pic of it:

http://maurord.altervista.org/_altervista_ht/mitofinita1.jpg

If you want it to make power at high RPM, the short pipes will be OK, the problem arises if you want a lower powerband.

Those pipes look way too small in diameter to me. I can't see them doing too much good. It looks like he has kept them small purely to avoid work on the subframe, seat unit, give clearance for the shock, etc.

That guy has also got himself into a real mess with the rad and carbs there! - I'm sure he could have put the rad somewhere else!

Really, to take full advantage of the layout, you want the carbs to shove their mixture straight into the crankcases rather than going through the barrel. Then you can get another transfer port in there too. It would also make the carbs easier to fit in and that is how Yamaha did it.

Yamaha didn't cross the pipes over on the 3MA, they just put a slight bow in to make them a bit shorter. Here is a set on Ebay: Ebay link

In my opinion, if you want to do a reverse cylinder bike, you'd be much better off buying a 3MA engine and you might be able to bring the bore up a bit, maybe 300cc or so.... I'm pretty sure people have managed to acheive 70+ hp.

[wazrs257]

YPVS engine just surfaced on the bay.

Just off to send an email...

Are you the proad owner of a YPVS engine yet?

[stuntmonkee]

Nope, he never replied as too whether I could pay by Paypal or BACS and arrange a courier.

Hohum wait for another one

[wazrs257]

Nope, he never replied as too whether I could pay by Paypal or BACS and arrange a courier.

Hohum wait for another one

Oh well, better luck next time mate.

[stuntmonkee]

while I'm here anybody know the weight and L/W/H of a YPVS engine?

[Rich]

while I'm here anybody know the weight and L/W/H of a YPVS engine?

Haven't got the dims to hand but a YPVS engine weighs about 38kg.

[stuntmonkee]

Fuckit-thats a pallet not a box and 2.5 times the cost of the courier

[paul8899]

getting the engine rebuilt is expensive as well, if your going to the trouble of building something a bit special best to getthe engine sorted as well.

Mine needs the barrells relining ( £250 for the pair ) the crank rebuilding ( £170 for just the big ends and rods or £330 for a new one ) when you add the pistons,bearings and gaskets its getting near £800 , don't forget thats back to standard spec. Might be better (cheaper) to get the whole bike and take the running engine out.

[eddie]

Or just go the whole hog, and buy a 611 Cheetah kit from Trinity Racing, and put it on a ypvs bottom end (hope you got plenty of money!)

After youve looked at their website, check out Matoon machine.........................

Oh and The Two Stroke Shop (in aus)

If you havent already

[stuntmonkee]

I'd rather rebuild an engine personally, at least I'd know it was right then.

[dougb]

a mate of mine is selling his 350 mito,i've helped him with it,very similar to mine......

125cc sportsbikes

[stuntmonkee]

Don't show me things like that.....

[paul8899]

I'd rather rebuild an engine personally, at least I'd know it was right then.

I'm going to rebuild mine myself , the prices were just for the parts !