Buying and worried about carbs

[ajay]

My goal is to buy a CB 750 (k2 ...) in the coming months. There are plenty on the market, in all states. It just depends on how much I invest. While none of the expected tasks (pre-buy, initial work and long-term maintenance scare me when it comes the an SOHC oldtimer, there is one thing I am not quite so confident and that is the carburetors.

1) in a typical pre-buy situation there is limited time. So all I can do is check engine start (cold and warm), look for leaks and outside damage, ride the bike. But such may not be enough to avoid soon to arrive problems.
2) work on the carbs, frankly after reading upon it, I think a complete overhaul may be beyond my skills and available tools.
3j finally, even if the carbs were in good shape, and if properly handled, can I keep them in this state for more then just a few years ? ... or does one need (expensive) expert help every few years?

Thanks!

 

[ajay]

?? Really nobody with any relevant (uplifting) experiences?

 

[jryan19]

I would like to buy a CB 750 also. It seems you have to plan on doing the carbs. I test rode a 1979 model. The guy said it ran great. It was very lean and cold blooded. Didn't want to respond to the throttle. Had a buzz in the bars at all rpms. I thought they would be smooth. That bike may have had other issues. I think rejetting will be mandatory for any one I buy from 1979-1983. Am I correct ? Anyone ?

 

[scubanerdnick]

?? Really nobody with any relevant (uplifting) experiences?

I had a 78 750K model that I had the carbs redone on in 2006. At the time they were worked on they were gunked up bad from sitting for several years and while the bike would turn over and all it was not running well at all. I had a local guy take care of them which entailed having them ultrasonic cleaned, replaced, and tested/tuned. The mechanic also did some other tune up work to it to get it running really well. Once that was done I ran the bike regularly for over three years with no issues at all from the engine. When I sold it in 2009 it was still running great, I had simply wanted something new.

So my two cents on all of this is once you have bad carbs cleaned properly and then replace, tested/tuned, they are unlikely to cause big problems as long as you're treating the bike right. In my case this meant turning off the fuel when riding season was over and just generally running high end fuel (ethanol free or at least premium with occasional additives). Personally I would not let carbs deter me from buying another CB. They are generally easy for a professional (and some novices) to service even if you do have problems.

 

[dirtdigger]

The sohc carbs are about as basic and simple as they come. If they are just dirty, they can be cleaned with just removing the bowls and the jets, etc to get them working. If parts are stuck, broke etc them it gets more complicated if you have to split them apart.

 

[DaMaFan]

?? Really nobody with any relevant (uplifting) experiences?

Greetings. I recently acquired a K5 with K8 Keihin carbs and was able to successfully rebuild them and the bike is running now. The key is finding a good manual and follow the steps but also watch YouTube videos multiple times. There are excellent resources online through this forum so take advantage of those as well.

As long as you research, read, organize parts, follow instructions and clean, clean and clean again to ensure all passages are clear, the job is not too difficult if you don’t rush through. Also, there are instructions for bench setting your carbs so the bike will run before balancing.

Note. I am a novice and salute the veterans who know volumes more than me so I am only sharing my experience and what has worked for me so far, but in no way claim that it is the right or best way.

Buy one and have fun with it. That is the point! Cheers

 

[Floshenbarnical]

No need to be worried about carbs tbh. I rebuilt a set of PD41As, with no prior mechanical experience by following youtube vids and forum posts. You'll need a good carb rebuild kit to replace gaskets, o-rings etc. Only buy jets from JetsRUs, everything else is cheap crap that isn't manufactured to spec from my experience. Do not try to separate the stack unless something is broken, or a slide is stuck, or something. you can do all the cleaning you need without cracking the stack, and frankly getting them back together correctly is a pain in the neck.