85R Top End Rebuild and Upgrades

[El Camexican]

Like a 38mm keihin pwk? http://pages.ebay.com/link/?nav=item...d=400822321112

Exactly!!!

[oscarmayer]

wished I would have spoken to you sooner.
we race 2strokers smaller but still same principles. under racing conditions the v-force setups always wear out 2-3 times faster than the Boyesen as well as yes the Boyesen does provide better top end support and with that setup you have, you may want to reconsider if you have the opportunity. I have seen at the track a v-force shatter sending shards of CF into the cylinder ruining a good motor. I have not seen that with a Boyesen setup at the tracks.
just wanted to offer my $0.02 worth if it matters.
also with a larger than stocker setup you can call Boyesen and get thicker CF reed setup and ensure you will never have problems. we had to do that every time we go up past .25mm piston size on our race motors. If you call them you can order it to handle exactly what your doing right out of the box. they even did a custom mod to a cage for us when we were running an Athena setup as the Athena inlet came deeper into the intake and was also a slightly longer intake run than stocker. Honestly it's that type of stuff is the reason why we are sponsored with them instead of V-Force. V-Force would not do anything custom or help us when we asked about stuff that needed modifying.

good luck. looks like a very fun setup for sure!!!

[Samjp22]

I really need to get some swing arm stickers made that say "Money Pit" that's all my dad (coolpool) calls her and she sure is living up to her name! Lol

[oscarmayer]

LOL yea, performance bikes, trikes, quads are expensive. But if you build it for reliability, you spend FAR less than if you cheeped out and redid stuff multiple times in a short period.

Old saying I live by.
Fast
Reliable
Cheap
You get to only pick 2 of the options......

[Samjp22]

Just read your longer reply, I'll give the vforces a try! Appreciate all the input, if they don't work out boyesen is next in line

[Samjp22]

38mm and 39mm keihin are basically the same price, probably be better in the long run to go with the 39? From reading around it seems more people go with the 39. Will using the stock air box (not drilled) and uni filter restrict too much airflow to this carb? Is an airbox delete needed?

[oscarmayer]

I recommend you get with twin-air and order you some filters for air box lids. The reason why is with that much of an upgrade the stock air box cannot flow what you need. so you have limited options
1. remove lid and run w/o it
2. drill holes and leave it
3. drill hole and sue Twin-air's lid filters
4. run a filter that connects directly tot he carb open style and remove the air box all together. (done for racing purposes). This is how we run my son's quads. We have a round filter hanging off the carb and open to everything. Then I put on an outterware net cover and call it a day. We race MX so we typically are not submerging or getting into that much water.

[Samjp22]

this looks pretty fancy http://www.ebay.ca/itm/EHS-Racing-at...cb211d&vxp=mtr
probably be the best thing to use if I go with the 39mm pwk

[oscarmayer]

perfect! looks like it is similar to the twin air stuff except rectangular instead of circles to be drilled out.

[Samjp22]

going to get a better idea on how this cylinder will run this weekend thanks to MTS! At least hes only three hours away

[oscarmayer]

cool! GJ gents!

[Red Rider]

If your new piston doesn't have the holes pre-drilled in it, to lubricate the exhaust bridge, I would follow Wiseco's instructions, which should have come with the piston, and drill your piston before you run it.

[Samjp22]

New piston has pre drilled lubrication holes thank God, wouldn't want to have to drill those lol

[Red Rider]

New piston has pre drilled lubrication holes thank God, wouldn't want to have to drill those lol

That's what I thought the first time I had to do it, but it's really pretty easy.

[Samjp22]

yeah their instructions seem pretty straight forward, just weird how they wouldn't do that from manufacture