Custom V-twin from two singles

[Tints]

I'm building a Custom 90 V twin from two Yamaha 250 dirt bike engines for a small race car and have hit a small problem with the head bolts.
The problem is with the new crank case that has been machined the old bolts are too long to fit ( they sit under the cams) and so I need to find some new ones. The bolts need to be the proper yield bolts with a wasted shank, forged etc. Does anyone know of a bike engine that uses a 110 or 120mm long bolts that has a thread of either 9 by 1.25 or 10 by 1.25.
I have talked to ARP bolts and they don't have anything in the right size. does anyone know of any other companies that might do them?

Bellow is a picture of it made up with its dyno crank case (there will be a trans axel built later.) The crank is being balanced at the moment and we hope to run the engine in about 3 weeks.

[jonbuoy]

Impressive work there

http://www.aperaceparts.com/
http://www.northernautoparts.com/Pro...?ProductId=334

These guys might be able to help. They seem to call them cylinder head studs in the states.

[Macktheknife]

Any reason you can't just cut them down to size?
Failing that try MSL in Rosebank road, Avondale or Atom fasteners or WDS in East Tamaki. There is also a nut and bolt shop on Constellation Drive but I can't remember the name of it, almost last on the right heading towards East Coast road.

[Buddy L]

i was just going to sent you this link
http://www.fsae.co.nz/
tell you to talk to people a Auckland Uni.
But then i saw you profile. and found out that you would be talking to your self
You know that would make a nice Formula 3 motor, to slip into a RS125 frame

[Buddy L]

Are you using two WR250f motors?
or the YZF250?
Why the change from the R6 motor?
trying to get a flatter toque curve.

[slowpoke]

Sorry mate I can't help, but I've got say what an awesome effort that thing is. I'm guessing if you shorten the bolts you've got you won't have any thread left so I'll leave that well alone.

Oh yeah, once you've finished with that tiddler could you knock me up something similar with a couple of Husaberg 650 cylinders when you've got a spare 5 minutes? Ta....

[surfer]

The 'bolt shop' in near the police station on one of those roads off Wairau Road are excellent for bolts. Never seen two old guys happy as dealing with bolts all day long.

[Laava]

Nice job mate! Got the exhausts facing in towards each other.........not thinking of putting a huffer in there are you?

[JeremyW]

Are you using two WR250f motors?
or the YZF250?
Why the change from the R6 motor?
trying to get a flatter toque curve.

YZF250. Yea basically because we are looking at dropping a lot of weight (hopefully down to about 170kg) and the best way to do that is run a very small engine. A few teams successfully run 450 singles but we would like to make the best of the torque a V-twin configuration gives. As we are limited to 610cc and no-one (except Aprillia recently) makes a high performance V-twin we thought we would make life very hard for ourselves and make our own engine.

The R6 is an amazing engine and with the supercharged / dry-sumped setup is unbelievibly tourqey! But it is a bit of a pig at around 80kg for the entire system!

Tints is doing it as his 4th year Uni project and has got is remarkably far from where he started I cannot wait to see it on the dyno.
I am pretty sure next year we will be designing around this little beauty... Watch this space!

[R6_kid:Me]

best of luck guys! I remember being told about your plans with this last year, looking good so far... my R6 engine was 60kg all up minus carbs and headers... how heavy was the supercharger kit?

[JeremyW]

We have our own fuel rail with injectors, piping, carbon maifold, supercharger, supercharger bracket, drysump pumps, ds tubing, ds tank, radiator etc etc all came to 80kg I believe. We also have a electronic shifter using a DeWalt drill motor and a fuel cut, makes for a shift time of around 0.15 sec (although could be less).

As it was the first prototype of the system it was all a bit bigger than it needed to be. Roll on this year

[JeremyW]

Some interesting photos

[Brian d marge]

If you can track down a book called Nuts bolts and fasteners by Carrol smith it A; has some great advice from a top fella , and B; all the places who sell top quality Nuts and bolts

I have all his books and they are Well thumbed !!

Stephen

[Tints]

I have found some Yamaha bolts that are shorter that can do the job (I will make the holes a little longer as well!)
Thanks for everyone’s help and suggestions, we are getting so close now, just waiting for all the crank bits to be finished, balanced and exams to be over!

i will post more details as things move along. Maybe I should start a blog about it... never done it before.... any suggestions...

The next problem is does anyone know of some small electric oil pumps? I just need one for the dyno setup to start with (the oil pump will be in the transaxle case) and the engine doesn't need much oil (being a dirt bike engine). I am going to try some fuel pumps but I think that I will burn them out. I have a funny feeling I will have to end up running a belt to a gear pump or trifler pump. Does anyone know how much flow the normal engine has?

[Tints]

P.S. also we weighed the engine the other day (the complete heads, barrels, crank and crank case, no gearbox)
and it weighed

17KG! its so tiny and light!