Topic: looking at a 74 CB750K this weekend ?'s

[Moondo]

I joined this forum with intentions on building a CB 750 Cafe Racer. I just recently came across a 74 CB750K that I plan on seeing this weekend, the guy that is selling it, says it runs great  and the bike looks nice in the few pictures I have seen. I would like to eventually go with an 836 kit in the future, and was wondering if I should have concerns that this bike has 81,000 turns on the odometer? Also any advice on other things to watch/look for?         

[harisuluv]

81k on the odometer?  Yes, CB750s are great, reliable bikes, that can go for 100k with little maintenance.  However, 81k is very high mileage.  Most of the bikes that I find have around 10k miles.  Something happens to them and then they sit for awhile and then something else goes wrong (ie battery). 

This prospective seller is going to say anything he can to sell you his bike.  Listen to what he says, but remember that it is in not fact, only his own account.  Inspect the bike yourself and make your own judgements.  He will try to tell you that 81k miles is nothing, and that it "still runs like a champ" or "These bikes will go for xxx,xxx miles easy."  The bike is high mileage, that is the bottom line, don't let him negate that bargaining point for you. 

[andy750]

I have a CB750K4 with 75,000 miles and it runs like a champ  

No really it does - engine rebuild with top end redone, well maintained throughout the years Ive had it (since 2001 and 40,000 miles since then). Its all about the maintenance. Buying a bike with 10K means it has sat for years....whereas a bike with 81K means it has been used (as intended). As long as its been maintained I dont see an issue. Mine has another 50,000 in it before any more engine work . I am planning on some bike trips with this bike.

If the price is right and the owner has some records for maintenance then Id buy it.

cheers
Andy

[Stev-o]

Ask if it's been rebuilt. If is hasn't, keep in mind it most likely will need one. And you can drop some coin doing it right.

Good Luck.

[HondaMan]

Mine has 140,000+ miles on it, just coming apart this winter for the first major rebuild throughout.

Things to specifically ask about on the K4:
1. Ask if it has any "jump-out-of-2nd-gear" issues. If so, the bottom end will need new 1-2 countershaft gears and new transmission bearings if you go up to 836cc, as the current ones will have slightly rounded dogs and the shifter drum will be worn in the 1-2 shift pattern. This is entirely normal wear: if you were staying in the realm of 750cc or smaller (i.e., stock overbore sizes) it would not be a serious issue. The 836 will make it an issue, though.
2. The primary chains will be pretty used up, especially for 836cc increases.
3. The valves will likely need a light valve job, but if you're tearing into it, that should be considered anyway. The K4 top end is very reliable, but it does wear its rocker shafts quite a bit, so it may sound a little rattle-y up on top, especially when warmed up. This is normal wear, and not a problem unless you're heading for 8000+ RPM work: then you should replace the shafts and possibly the rockers, for best performance.
4. You will probably find oil leaks in the following places at this mileage, unless it has been re-sealed:
a. Tach drive at the cam cover.
b. Countershaft (where the chain rolls on the primary sprocket).
c. Points seal (a little, not a lot).
d. Oil pan gasket, making a greasy mess under the engine and on top of the pipes.
e. Possibly the bottom of the head, where it meets the top of the cylinders, from 30-year-old Orings that are getting tired.

Overall, I would consider all of these issues to be normal on a K4, and if any are missing, an exceptional bike if it is virgin. I have seen many in this condition that took little cash to make into excellent 750s again.