Starter bolt broken off in case...

Hey Everybody,
I have a 1981 XJ750 I just acquired and have been going thru some wiring issues with it, but just noticed something yesterday. There appear to be two bolts to secure the starter, I am guessing different lengths, the one on the left as you are looking at the starter is longer. When I got the bike it only had one bolt, the one on the left; I went to turn it with my fingers, and it was loose and came right out. That's when I noticed that this bolt only had less than a quarter inch of threads on the end, and had obviously broken on the threaded end, possibly in the case where it threads in to. The other bolt on the right side was missing entirely. I am not sure what is behind the cover where the bolts go, so I have not removed it yet. I ordered a factory manual on fleaBay, but have not received it yet, so I thought I would ask if anyone has ever had this happen? And if so, what did you do to fix it?

Thanks!
Skip

 

Both of those bolts also secure the lower case to the upper case and there is a transmission bearing directly below and between those two bolts. Get thee to a machine shop so a proper repair can be done. They may be able to remove the remainder of the broken bolt without needing to tear the engine down. Be sure to have them inspect the other hole for missing threads, and to install an insert if needed.

 

Oh noooooo, say it aint so. Bike is still in the "trying to figure out the wiring mess and get it running stage", so I guess if I were going to take the engine out of the frame to paint the frame, now would be a good time to do it, so as to more easily transport the motor to a shop...

 

The engine is very heavy to carry. Personally I prefer the easy to use two-wheel dolly that the engine comes in from the factory. In fact it comes with a mechanism in front to allow you to steer it around, as well as brakes front and rear to manage rolling speed.

 

But a machine shop will want the engine out of the frame in order to do any work on it. Still it's worth rolling the whole bike over for a quote before pulling the engine.

 

But I have Psycho (or is it Psychic?) powers... I can just look at the motor and move it with my mind...

 

I totally agree that the right and correct way to fix this is to do what k-moe suggested and take it to a machine shop. I am still waiting for my Yamaha FSM I got on fleaBay to come, hopefully next week, so I do not know what the motor looks like under the cover (the one under the starter...transmission?) but in the spirit of just speculating out loud, would it be feasible to remove the starter, and on the left hand hole, with the long/broken bolt, just tap some threads into the top on the case, get a bolt to fit, about 2.5" long like the right side, and call it good? You would also have to bore out the left hand mount of the starter to accommodate the slightly larger diameter bolt, but would that not work?

 

no. simply put, those bolts hold bearing journals together. without them, the journal can spread and cause bad things to happen. which could have already happened since the bolts are either broke or missing.

FU

 

YUCK!!!!! Definitely not a diy job. You also might want to keep an eye open for another engine.

 

Or another set of cases. They can be had for 1/3 or less of what an whole engine costs. At this point I think it is foolish to put a used engine in without splitting the cases and replacing the primary chain guide and rebuilding the starter clutch (at the minimum). They are all old enough that the work should be done preventatively, and it is a good opportunity to do it if the engine has to be out for some other reason anyway.

 

it seems to me i put a helicoil in for the long bolt while it was on the bike

 

Crap... why on Earth did I think this would be easy. Maybe Ill just yank the motor and put in that Harbor Freight 5hp Chinese motor I just bought for my air compressor...

 

If I pull that engine cover under the starter is what you are talking about visible? Do I need to drain the oil to do that?

I just saw a set of cases on fleaBay for $28.00, plus $25.00 shipping, he has them listed as a 1981 xj750 Maxim... is that the same motor as a Seca?

http://www.ebay.com/itm/1981-Yamaha...ses-/400876246560?hash=item5d56161620&vxp=mtr

Thanks!
Skip

 

The cases have to be split to change the primary chain guide and rebuild the starter clutch. DO NOT do the work without having both the Haynes manual and the Yamaha shop manual on hand. That is a good price for the cases. The only difference between the Seca and Maxim cases are the motor mounts, and adaptations can be made to fit Maxim cases into a Seca frame (and probably can be done the other way around). Be aware that you will almost certainly need crankshaft bearing shells and shims for the middle drive gear and output shaft (bearing shells are costly). This is not a small job (not terribly difficult, but very tedious), which is why I recommend that you have a machine shop look at the problem to see if it can be solved without tearing the engine down. No matter which way you go you will be spending more than $50.00 to get this fixed correctly.


EDIT: The engine mounting lugs on that set of cases is for the Seca. It looks like the bearing shells come with the case, so you might get lucky (as I did) and only need to swap a few bearing shells around to fit your crank into the cases. Regardless, my advice above still stands. Get thee to a machine shop.

(it might not be a bad idea to snag those cases anyway just to have on hand)

 

You probably did, but by the description given the long bolt broke off inside of the hole. Extracting the remnant is going to be tricky.

 

What I am curious about is how that could have happened in the first place? I didn't look that close at the broken bolt, but if it is a case bolt, its got to be like a grade 8 or so?

 

Did you put the heli coil in because you had stripped threads in that hole?

 

this is really taxing both of my brain cells but it might have been a through hole
yes the aluminum threads were gone. no need for a strong bolt if it's in aluminum

 

Hey...does anyone happen to know where I can source one of those long starter bolts for my 1981 xj750? Yamaha part number appears to be 95811-06120-00, I have looked at all of the usual places online, but all the messages say 'obsolete'. I found a machinist near my house I am going to talk to about it, but there is really no point in even doing that if I cant source a replacement bolt!

 

I think I might have answered my own question. I was looking thru the for sale section on this site and someone was talking about motorcycle salvage yards... *D'OH*... I cant believe I did not think of that (actually, I guess it never occurred to me that there was such a thing!) There are a couple here in Tucson, so I guess it is worth a shot. I also need some parts for a 1978 XS750 triple I am not having luck finding, soooo...

 

Put a thin feeler in the hole and see if anything is in there ...... Maybe the rest of the bolt isn't even in existence

 

Yeah, I checked that. When I first got it, that bolt was just sitting in the hole, the flange on the bolt flush with the top of the starter. I tried sticking a long thin piece of wood in there, and yeah, there is something in there, or it could just be the bottom of the bolt hole.

It has occurred to me that just because there was a broken bolt in the hole does not necessarily mean that it came from *that* hole. I took a tiny light and looked down in the hole and I can see what is either the bottom of the hole, of the top of a broken bolt. Also, it *appears* that I see threads in the bore before the bore bottoms out, but it is hard to tell because of the depth. What is not helping is I can find *no* information about the bolt; diameter, length, etc. And no one is selling them, so I am at a loss.

That Harbor Freight 5HP gas motor is starting to seem like more of a possibility to me. Maybe I could start a new trend; Chinese engine in a Japanese bike, call it a Chap

 

If Len doesn't have it (username Chacal), Ebay will. Several of the forum members also have stashes of parts so you could put up a request in the wanted section.

 

put your stick back in the hole and mark on the stick how deep it goes. then measure that against the broken bolt. that will tell you if the rest of the bolt is in the hole or not.

FU

 

FU...I tried that already but I am not sure what it is telling me. I did take the starter out so I could get a better look in the hole, and I can put that bolt in the hole, take the starter and the end where it mounts will *just fit in there, in between the starter and the case.

 

Good Idea, Ill try that first... been looking on fleaBay, and nothing yet.

 

Sometimes the small stuff will show up in parts lots. You have to look closely at the photos to find what you need.

 

I just looked at Chacals parts list....*yikes*, what a great resource! He has no less than three varieties of the long bolts listed, just waiting to hear if he as the short ones...and while I am at it I might as well make up a list of other stuff I might need