Couple R questions

[krizo88]

I tore down my 85 R a couple nights ago, and i have a couple questions. I was wondering what kind of swinger I have, its chrome, and it is kind taller in the middle section and towards the bearing end it rounds out and gets smaller (i dont have a digital camera so i cant get pics). And I want to give the motor a little more snot, it already has a port and polish and a 38mm carb, reed spacer, and UNI filter. Whats involved in putting a high compresion piston in and possibly shaving the head? Any mods you can think of would be considered. I was going to put a big bore kit in, and decided not too ( a little more than what i wanted to spend). Also are Showa forks stock on this machine? Thanks Chris

[Jeb]

Showa forks are stock. Your swingarm sounds like it shaped like a westcoast. they start out small at the pivot and get larger toward the carrier.

[TRI-Zbrian]

you could put an aftermarket pipe and silencer on it. also plaining the head is not a big deal you take your head off and find a machine shop in your area that is good at what they do and tell them exactly how much you want shaved off. with a plained head you will notice a bit more bottom end.

[Wickedfinger]

Dropping in a higher compression piston is easy, but are you sure it dosent already have one installed?. If the case is that you had the work done yourself, then skip this next part ..... If you didnt, then I'm assuming when you bought the motor they said is was ported but I have to ask, how sure are you that it really was?. While its very possible, I still would be suspicious that someone would take the time and money to get Jug work done and not throw in a Wiesco or Nik's higher compression piston with hotter piston porting in with it - but - some people like the thought of using stock pistons because they think they are more reliable. The head work you want to do is called "Tightening the Squish" and any good shop that does porting will be able to do it for you - but be aware that if you go too radical and take away too many cc's of volume, you will really need to consider using race fuel and the bike wont be as reliable and will be a bear to idle.

[krizo88]

well, i havent got into the motor yet, but when i bought it the guy gave me some carbon copies of the work that was done at one of our local machine shops, and a receipt for wiseco piston and rings from our local dealership, he gave me all the paper work on it that he could find, unless the paper work was for a bore I dont know what else could be done to acumulate a 230 dollar receipt?? I suppose I could find out by taking the top end apart, but i wanted to get everything else done. But thanks for the info gentleman. Much appreciated! Chris

[KASEY]

THERE is no such thing as a high compression piston for a two stroke engine,,, a wiseco piston has the same compression ratio as stock,,to change compression you change head gasket thickness mill the head or deck the cylinder,,,,,, a piston change alone will not do it,,,,,,,,

[Wickedfinger]

Actually KASEY, I thought the same thing and for the most part you are correct in the case of the ProX piston - they are lighter and stronger than a stock OEM piston, but they retain all of the same power as stock too. Wiseco on the other hand is a little different - a few years ago I e-mailed Wiseco and asked them how they were able to claim a 2 hp raise in horsepower on the Scrambler 400L engine just by installing thier prolite piston. Thier response was that it was accomplished mostly by correcting the piston ports timing from stock and by a slightly more radiused crown than stock. The radiused crown does increase the compression ratio by a bit ..... but would I call it a "High Compression" piston, no, and typically, the terms Hi compression piston and 2-stroke are not associated with each other except in the case of head cc's - so you are correct to a point and it just points out the dangers of mixing 2-stroke and 4-stroke terminology - the correct wording should have been "Higher Performance" piston instead of "Higher Compression" piston.

[ChrisD]

The cheapest way to raise your compression is to have someone mill your head. You are talking $40 to machine the head and a $5 gasket. You can also get a cool head with interchangable inserts to give you different cc domes. I personally bought an FTZ 19cc head for my old race motor and loved it. It had a better shaped dome than stock. I ran at about 225lbs compression. I shaved the head on my woods bike and it worked well though. $200 vs $40......you decide.

If you do this, be prepared to spend a lot of money on gas. I think I pay about $7-8 a gallon for VP C12 for my bikes. I think the cheapest I can get gas is $5 for Sunoco 100 octane fuel. Before you spend $40 every time you go riding, make sure why you're doing it. If you ride in the trails, then don't bother. If you ride in the dunes or race it, the go for it.

good luck.