Join Date: Feb 2007
Location: marion, IN USA 46953
Seeking VTR250 Interceptor info
Hi all! Came across your great site here while searching the web for VTR250 info. From the posts I have read, it seems Lord Duckhunter is the VTR master!
My 1988 model is still pretty much stock, about all I've done is install the Dynojet stage II jet kit and a Yoshimura slip on with the baffle removed. Also cut the old paper filter out of the filter plate and dropped in a K&N flat panel air filter from a civic. She runs a lot better than stock, but I recently acquired a 1990 model as a project bike and want to go a bit further on it.
Had a few questions for anybody who has upgraded their VTR, I'm hoping your experience can save me some time and cash. The bike came with the VTR specific Supertrapp muffler, so I do have some adjustability on the exhaust side of things.
First, which is the better jet kit, the Factory Pro or the Dynojet? I'm pretty happy with the Dynojet, but have zero experience with any of Factory's products. I plan on adding the K&N air filter to this one as well.
I'm planning on putting in the Progressive Suspension fork springs but I have heard mixed reviews on these. Greatest mod ever or a waste of money? I am a little heavier than the average rider if that figures into your advice. Also, the Race Tech cartridge emulaters are available for the VTR forks, is this a worthwhile mod?
Internal engine mods is where I am a total newbie. I have a mill and lathe so simple machining like slotting cam sprockets and such would be easy, but extensive specialized mods like lightening the crank is out. With that in mind:
The Japanese domestic models with this engine crank out 43HP according to the literature. So far the only two major internal differences I can see comparing specs is the cams are of a different grind, and the ignition timing is advanced something like 5 degrees. Is this correct?
Are the Japanese spec heads different other than the cams? I have seen some claims that the valves were 1mm larger and that the internal passages on the intake side varied somewhat between models. I can purchase cams fairly affordably but was wondering if the head should be swapped out as well for maximum effect. Is there a better alternative to the Japanese cams? Slotting the stock cam sprockets and adjusting stock cam timing? Looking for streetable horsepower here, not an all out race bike.
I plan on slotting my starter clutch cover to advance the timing, what is the general range I should set it to for maximum power using premium (93-94 octane) gas, stock compression and possibly Japanese spec cams?
Any other mods that would be worthwhile and inexpensive?