Mikuni I-Series Woes

[dtd696]

Well, Here we go again. I just got done reviving an xl1200 from sticky carbs by replacing the #2 carb due to bad bushings heating up and binding up the throttle shaft. Now we have an 00' XL800 doing the same thing. This time I honed out the bushings until they do not bind anymore. Man, thats nerve-racking. I would hone a little, install the shaft, heat, then hone some more until no more binding.
Has anyone else had success with this procedure?
It did not take much to cure the binding. If fact my Mic barely measured a change .0005. I shoud get this thing back together by tomorrow and let anyone know the results if they want.

[dav_dman]

Re: Mikuni I-Series Woes

is there a kit for this? the throttle plate screws would be good to get with it.. and how do you ding em after the final install?

[Technical Support]

Re: Mikuni I-Series Woes

No there are no i-body throttle shaft kits for some stupid reason. Every other carb has them available. Drilling the bushings is a VERY dangerous thing to try - a leak there can easily lean out the engine.

[dtd696]

Re: Mikuni I-Series Woes

dav_dman - I brace the shaft with a wood dowel on the bottom side then tap the threads of the screws with a flathead screw driver just enough to flatten them against the other threads.

I would not suggest "Drilling" the bushings either. I am using a dowel with sand paper and valve grinding material.

I did come accross another post where someone did this with success. I forgot the user name though.

[David3aces]

Re: Mikuni I-Series Woes

Do the bushings get tight due to the carb corroding?

[Technical Support]

Re: Mikuni I-Series Woes

Yes, due to lack of maintenance.

[dtd696]

Re: Mikuni I-Series Woes

I don't think I completely agree with that in all cases. (Nothing is absolute with these things anyway ;) ) Poor maintenance certainly played a factor in the XL1200 I mentioned because it looked like that thing had been sitting for years. The carbs were pretty gunked up. However, This XL800 has been well maintained and the carbs were very clean.
I have asked many people about the history of this problem and no one knows exactly why some do it and some do not.

[Technical Support]

Re: Mikuni I-Series Woes

They may be clean, but I bet they were sprayed with oil very often. Those bushings require lube just like bearings.

[dtd696]

Re: Mikuni I-Series Woes

Well, Got the carbs back on and fired this thing up. Sounds good so far. Smooth Idle. I ran on the hose for about 5 min. Checked the plugs and they are starting a nice tan color. Does not seem like any low speed "leanness", so far, from boring out the carb bushings. Don't think I can get it on the lake today (rain, rain, rain), But will do soon. Wish me luck. No offense, but I really do not want to order a motor from SBT just yet :o

This is just in case anyone really cares

[chris w]

Re: Mikuni I-Series Woes

This is one of the reasons I like to add just a little lube to the fuel as pre-mix on top of the injection. I use .8 oz per gal on my Sea-doo.