PDA

View Full Version : budget motor?


riggsracin
09-23-2010, 10:00 PM
i just got an 86 , the current mods are
sst fmf exhaust, boyseen rad val, bored 20 over with oem honda piston. its an 86 cylinder stock, whats are some of the tricks and tip for some free or cheap hp
89trx250r
09-23-2010, 11:18 PM
have the cylinder ported to your riding style would deff be an upgrade idk if that is cheap tho but it depends on your budget
rustyATV
09-24-2010, 05:33 PM
Use the ATC250R head gasket for a little more compression.
wilkin250r
09-24-2010, 07:46 PM
Two-strokes are often cheaper to mod than the 4-strokes, but I don't know if that qualifies as "cheap", and certainly not free.

A good port job will run a few hundred bucks. Because it involves reaching into the cylinder with tools, and grinding, I generally get a bore and piston at the same time, which adds to the cost. But talk to your engine builder, he might be careful enough that you don't need that extra cost.

The beauty is that this $300 will get you more horsepower than a $500 engine kit for a 4-stroke. Less expensive, but I still don't think this falls under your category of "cheap".
riggsracin
09-25-2010, 12:16 AM
i have heard of using a cr250 head gasket, i know on a 400 ex u can take the base gasket out and use a xr400 cam and jet it and have the fly wheel shave and it will really wake them up. just now got an r always been around them and wanted one.
rustyATV
09-26-2010, 03:57 PM
Originally posted by riggsracin
i have heard of using a cr250 head gasket, i know on a 400 ex u can take the base gasket out and use a xr400 cam and jet it and have the fly wheel shave and it will really wake them up. just now got an r always been around them and wanted one.

A 1985 ( I think) CR250 head gasket, OR you can cut one of the two thin sheets off the ATV/TRX head gasket at the rivet, since they're all the same or similar thickness (the middle piece is just a spacer).

The issue with that, though , is with the stock cylinder head, you're going to build up too much compression.
riggsracin
09-26-2010, 06:24 PM
any other mods? need some porting pics it has an 85 cylinder on it stock orginal sleeve 20 over. i think i want a mid ranger bike