Could my XT350 be restricted??

[Starbuck]

I've been having running problems with my 1994 XT350 and now it has conked out altogether, but that is due to problems with the float and valve, however, when it was running, it felt really underpowered and getting it over 60mph was impossible unless you were going down hill with a tail wind!

I haven't had the bike long and it has become a bit of a project so I am yet to experience the bike and handling properly. Someone mentioned that the bike may be restricted to 17hp as the later years were for some reason. I tried to find some specs for this online and all I have found is details for a 1992 model which does state that it is restricted to 17hp.

Is there anyway to check if it is restricted and more importantly get round the restriction it if that is the case? I am looking to do motorway miles on this bike through winter so I don't want to be struggling along at 55mph on a good day!

Thanks!

[magnum pi]

A friend of mine had one years ago his was restricted i had a old T B M bike mag that told you how too tell if you had a restricted one and im sure its something simple as changing a part over between the carb and the engine if you bare with me ill have a look in the loft for the mag tomorrow.

[Starbuck]

Thank you that would be brilliant.

[Will]

They are restricted in the inlet rubber if you take carb off and look the rubber has much smaller inlet , i think you just buy one from older model but check with yamaha dealer or wemoto

[bull]

well i dont know much about it, but i have heard talk over the years. so heres my 2 cent, i think their is a few ways of doing it. one way is putting small washers between the head and exhaust down pipe. another is putting smaller washers between the carbs rubbers and the head and another is putting a smaller opening into the carbs from the airbox. now i might be wrong in all of that. also i think they some times put on a smaller exhaust, so see if your exhaust is standard issue

[peterekins]

They are normally resricted in the inlet manifold, If the hole is smaller than the overall bore, theres your problem. You can carefully bore them out, but better to get a new one, avoid second hand as they can perrish. also check the carb jetting, wemoto should do a carb refurb kit with all the nessasary jets, as you may need to change as well.just check if there is a difference between model years. Is it an import? Good luck.

[Beam me up]

My 1991 XT wasn't restricted but I'm told that it is simply something in the inlet manifolds that you may be able to cut out. Also some owners claim that removing the rubber snorkel on top of the airbox improves power and drilling a few holes around the outer edge of the silence outlet helps (on the original silencer).

[Starbuck]

Thanks for all the suggestions. I have got to take the carbs off to strip down anyway so I can check the inlet manifold then. Seems plausible as I can't see the bike operating at full power and struggling to reach 60mph!

Does anyone know the reason behind the restrictions? Seems silly to produce a bike with X amount of power only to limit it when it's not exactly a deadly speed machine!

Just priced up the inlet manifold rubber kits, ouch they are not cheap! Will do some more shopping around me thinks...

[peterekins]

Take the inlet off, get yourself a dremmel and just be carefull. I did the same on the XJR, as they were restricted for the french market. Also worth joining an XT forum, other model inlets might fit. Also check valve clearance, the cam can wear quiet badly, worth a check.

[magnum pi]

Hi found the mag it was a question and answer page in a feb 2000 in 1991 yamaha Restricted the xt350 from 31bhp to 17bhp (god no's why )by fitting restrictive inlet manifolds with a metal web which reduces the size of the intake bore, they say the simple way to de'restrict is to order a pair of unrestricted manifolds (their are two bacaure of the twin carb set up!)then you open up the air box and re,jet and that will give you 31bhp. hope that helps.