help with 75 gp433g

R

relicx440

New member
Joined
Jan 2, 2013
Messages
6
Age
37
Location
belleville, ontario
i recently purchsed a gp433, bit rough shape but seems to be solid engine although the carb is leaking fuel around bottom gaskets, seems boggy at take off to then it all of a sudden kicks in and goes like hell, so basically i am wondering what carb i have to get a carb kit, and if mabye there is something bettr to use for carb, i plan on doing some fun vintage racing on some local ponds this winter with it so want to to be running good, all ppl i race with have merc trail twisters and they seem pretty quick so need to keep up, so all help appreciated from any fellow racers,

just remembering i am not going all out at least not this year but want litte tips on getting her working real good! :yam:

thanks
 

First, pull the outer Drive clutch bell off. You'll have to take the bolt out first,pull the cover off and then remove the snap ring. The outer sheave is under pressure from the spring and is held on by two half circle pieces- don't lose them! With the outer sheave out of the way clean and lightly grease the splines on the crank. If the clutch sheaves are rusty now is the time to clean them. Reassembly.
The above is Optional-but the clutch will work better if you do it and you won't wear out the crank splines which really mess up the clutching.
Get a New Drive belt. Chances are that will take care of your bogg.
You should have a Keihin Carb on it. You can get NOS Kiehin rebuild kits on Ebay. Aftermarket kits are junk!
Your GP is around 40HP. Merc TrailTwisters are 50+ . You'll need a good 440 Exciter or SS440 or better yet a 433 GPX To beat them.
Have Fun !
 
thats one thing i forgot i am having issues with the bolt that holds the primary clutch housing on keeps loosening off, and when you take the cover off all i see is 4 weights?? do you have to take the rest of the clutch off to find the spring? and you are talking about the clutch off the crankshaft of the motor correct?

is there any other carbs that might give me a boost, like will a dual carb setup and twin pipes from a gpx help out at all increasing my power? and mine is oil injected if it makes difference for carb?
 
took it off today and regreased it and going to order a belt next week, also got a carb gasket kit for my carb ordered today and should be here next week,

only thing i am wondering is were can you order the gasket kit for the oil injection diaphram on the bottom of the carb?

and any suggestions on some modificatons i could make to get a bit more out of the 433??
 
The oil pump under the carb? You may find seals at a yamaha Dealer if he's been in business since the early 70's. I replaced the seals in a 70 SS338 I restored years ago. It still leaked!
Sorry, no simple ways to get more power that I know of. You could look for a set of Carbs from a 71 SS433. 818 Stamped in the mounting flange. But then you will have problems hooking up your oil injection lever and it would only give you 2 or 3 HP .

Mark

Mark
 
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