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New 1981 DOHC 750 Four

1981Four

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Hey guys! I just bought a 1981 CB 750 Four. Its running, and i have to say it runs pretty well tbh. It has some issues but I have been working on them rapidly and making her run as smooth as she deserves. I recently did a 2 hour trip with her back and forth and she was awesome. I did notice that towards the end of the trip she was losing power, I mean the throttle was not accelerating as hard as it was let say 40 mins ago. I also have been trouble adjusting the idle rpm set and playing with the screw to adjust it when its cold and hot, yesterday i was stuck in a UPHILL heavy traffic for like 30 mins and it was hell, my iddle would turn off the bike i had to keep reving it up with the clutch on the keep the engine running, if i was in another place, i would have stoped and adjusted the carb screw but the traffic and hill didnt helped at all. Those are the only two things that i have "felt" out of normal for the bike, I have done 120 Km/H on her easily and no vibrations, she starts fast and sounds like a beast.

This is a personal proyect that means a lot to me personally, I understand that buying a new bike would have saved me thousand of headaches and even money in the long run, but this bike means the world to me and having her running crisp and reliable is a personal challenge I now have. This was my grandfather dream bike and he never had the opportunity to buy it much less ride it, now I have this gem in my garage and I want to create memories, learn to work on her and enjoy her until one of us is no longer in this earth.
So to keep this short (as possible), I have 3 questions:
1) Is there a good set of websites where i can shop for parts online? Im currently working in mexico but if shipping is complicated i can also work with my FL address.
2) Based on those 2 "problems" I have felt, is there anything in particular I should be checking? or having a professional check? I recently just ordered a 4x Carb rebuild kit, new Air filter and a full set of engine gaskets and seals. Those are coming in the next 2-3 weeks and will be applied top in 1 month. I also recently did a full fluids change and cables.
3) I know its not a lot of info and its a vague answer at best, but it would help me greatly: Based on the information we have, if I have to do any "big" work on her, what kind of budget should i be expecting to have? If I have to spend 10k on her I will, this is not a "financial" buy for me, I want my kids to drive this bike and enjoy her just as much as I will.
 
Hi my friend your bike sound great send a picture to the forum. With old bikes you have to start at the beginning, if you know the history and can talk to the previous owner can help. But to start with check your battery at a start of a run and then at the end of your run, then check if your charging system is good. The next job you must do is a compression test and check your valve clearance,there is plenty of information on this site to help you through these steps. I wouldn't touch the carbs until you have proved the above all ok. Regarding the idle, it should only be adjusted whilst the engine is hot (set to 1000rpm+/- 100) please don't mess with the carbs until all else proved it opens up a can of worms. Good luck with the bike, stay safe🇬🇧👍
 
As above.....re things to do and trying not to touch....
Re your issues...
Might also b worth draining and flushing the carbs several times with drain screw..and checking the a/c filter element..

Welcome..and hope it gets sorted
 
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Hey guys thanks you for your input! Will have those 2 things checked inmediatly at a local shop this week. I have been driving her a lot lately, as in 3 hours a day a lot. She runs fine, only two issues I have found is the loss of power that i mentioned earlier and the fact that when the engine is hot, i have so much trouble finding neutral! Its almost impossible sometimes! I'm guessing it has to do with the clutch adjustments and tweaks, since i was sure it was the oil but i recently changed all the fluids and filters.
 
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