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Big bore upgrade questions.

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surfish95747

Big bore upgrade questions.

Okay guys, I have a lot of plans I am trying to get sorted out for when this winter hits (Utah). With those plans comes a lot of questions (many of you have answered a lot of them already THANKS!).

Okay, along with a new Yamaha R1 front end, I will most likely be purchasing a Wiseco 823cc Big Bore kit from Cycle X. I have also picked up a set of CB900F cams to throw in the top to help with the displacement increase. I have a shop picked out to do the boring of the cylinders and will also be getting new cam chain tensioners when all this is done. Besides the new piston kit, bored out cylinders, 900f cams and a valve job, gaskets etc. is there anything else major that has to be done to the engine to get it to run perfectly? Do the carbs need to be rejetted for anything done to the engine? I do plan on getting a 4 to 1 exhaust system and know rejetting has to be done there.

Sorry guys I know this is a big question and I will continue studying, one of the sites I found a lot of good information is Satanic Mechanic. Anyways, what ever you want to add will help. Thanks!

PS I will be replacing the rings etc for the clutch just to refresh it. Does anyone know hoe to change the shifter rod (term?)? My little rod, the teeth that the actual shifter lever grabs onto and bolts onto are shaved off and the shifter lever is VERY loose. Do I have to tear apart the entire bottom end to get to it? Thanks!

1980 cb750k

TOOLS1

Re: Big bore upgrade questions.

Administrator

You should be fine with the modifications you have planned, but you might not need to do any re jetting. Run the engine, and read the plugs. On the shift shaft, you should be able to remove the engine side cover, the clutch, and some other small parts, and pull the shaft right out, then slide the new one back in.
TOOLS

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shinyribs

Re: Big bore upgrade questions.

Administrator

Tools is right on.

Re: your loose shift shaft. Th stripped splines is obviously a bad things, but the shafts do wiggle around a fair amount normally. Seems wrong, but it's the side cover that gives it it's rigidity. If you tug on them with the sidecover off they wiggle pretty bad, but don't sweat it, as long as it's not pulling in and out.