| Author | Message | ||
     Dueller |
Anybody ever have the castings at the front head break at the motor mount? Last nite while riding my M2 beater, apparently the left mounting bolt failed and the right side mounting casting snapped off. Fortunately the motor mount caught on the lip of the head preventing castarophe. Just curious if this has happened to anyone else? Oh well...wanted a set of Nallin's or some Thunderstorms anyway. BTW...does the sportster mount up top like the Buell? Wondering if there might be a market for them as is with the Sporty crowd. | ||
| Socoken |
Dueller, i snapped that isolator mount into three pieces once (wheelie gone bad) and just recently had one of the bolts break, causing the other to follow. both bolts snapped off clean at the head, no wheelies at all. i re-used the same bolts that were in it when i wrecked, so thats my theory on why mine broke. 'course, i have the t-storm heads, so maybe they are a better casting. the washer that sits atop the rubber isolator also broke, eating the rubber itself, and maybe it was the extra vibes that did it. the washer is a cheap POS and costs 30 bucks to replace, so i machined one out of tool steel. | ||
| Dueller |
Soco, I've broken a motor mount on this bike and I reused the mounting bolts when I replaced it. Probably would have been wise in hindsight to get new bolts. From what I can see the left bolt snapped off clean at the head causing the right side to fail at the head casting. It is funny how attuned you can be to the way a bike feels/vibrates. There was only a slight change but I immediately knew something was up, pulled over and saw the problem right off the bat. | ||
| Bomber |
this failure isn't unheard of (pretty good write-ups in the Knowledge Vault), but not terribly common, either . . . .. . it has happened enough, however, to keep me checking the bolts and front isolator weekly, however . . . . | ||
| Djkaplan |
Not sure about the new rubber mounted Sportsters, but the old solidly mounted ones do use the front head as a mounting point. | ||
| Sarodude |
If I understand things correctly, the failure prone mounting point was moved inwards on XB heads to alleviate that problem. You could always upgrade to XB heads and get an NRHS mount to adapt that style head to your bike. You did, however, refer to your M2 as a beater so maybe not... -Saro | ||
| Reepicheep |
JB Weld Baby! (if it is REALLY a beater bike)  | ||
| Rocketman |
Like Bomber said......in the KV. When this happened on my S1W, some years ago now, I fixed it temporarily for two or three months using Devcon and a longer stud in both holes. If you look closely at ALL the later tube frame heads and the way those bolts fit, you will find they are not screwed all the way into the hole but worse they actually stop where the casting starts to pertrude out from the mass of the head. IMO this is a weak spot, acting like a cantilever, so I bought high tensile bolts that threaded all the way into the hole. If like I did you find those bolts to long, I used spacer washers to mount them rather than cutting them down. This was the only way I could keep the shank of the HT bolt in the most optimum place. I used this set-up after I'd welded the broken head, and it now remains as a permanent fix. Good luck!! Rocket | ||
| Sportyeric |
If its an M2, wouldn't the heads already be Thunderstorms? And if that's true and if you decide to upgrade or otherwise replace, the Sporty's upper mount is kind-of optional, at least compared to a Buell, so while you might not find anyone willing to BUY them, damaged and all, you might find a grateful Sporty owner who could put them to use if they didn't cost much more than shipping and a bit. | ||
| Rocketman |
Hey, it's no problem welding that piece back on. Obviously the head needs to come off to do a proper job, but if you do it like I did, build it up with weld and smooth it down by hand, then repaint, it will work fine. Welding it will make it much stronger if you leave enough weld on the repair and it shouldn't be expensive either. Trust me, my head repair has worked. Rocket | ||
| Davefl |
Sportyeric, M2's did not get Thunderstorm heads until '99. Pre '99 had Lighting heads. | ||
| Dueller |
Thanks all for your input. It is a 97 so it doesn't have the TStorms. I may try just having it welded back and see if that is an economical fix for the time being. I'm sure I could pick up a used front non-TS head fairly cheap if the weld won't hold. Might as well go thru the top end while the motor is out of the frame if I don't upgrade the heads. I like the idea of the longer bolts to go all the way thru the casting. My first love is my S1W...this is a bike I was prepping for my gf to ride that I have used for a knock around ride when the Lightening was undergoing mods/repairs. Thanks again everyone. | ||
| Charlieboy6649 |
Just a question for the group on this topic. I heard the XB mount is designed so that if it fails, the engine will actually fall against the mount vice down onto the ground. Purposely done this way. True? Thanks | ||
| Socoken |
the motor in my M2 was hanging by the stock air box, a little unsettling, but no problems yet from it. | ||
| Dueller |
Charlie...I replaced my stock M2 mount with the X1 mount when I eleminated the breadbox. It did in fact catch the engine on the lip of the head/rocker box cover preventing the engine from falling further. | ||
| Charlieboy6649 |
Dueller, Thanks, maybe it's true? | ||
| Rocketman |
Here's a pic of the temporary repair. Note the bolt length. I left it long because the thread went ALL the way into the hole, deeper than the original bolt did, and that bolt you see is high tensile. Its shank length was longer than needed hence the spacer. Where you see the crack is where the stock bolt ends, but as I said the hole is deeper so there is room to cut more thread with a blind tap.  I just found this picture by coincidence and I don't know where my other pics are of the finished repair I eventually did. Looked great once it was done. I'll make a point of detailing this repair with pic's. Stand by! Rocket | ||
| Blasterd |
Guys you are starting to worry me, should I put longer bolts in or is there a way to safety harness the motor from falling out of the frame? Ken | ||
| Rocketman |
Ken, it won't fall out of the frame. The underside of the rocker covers will drop onto the front motor mount - catching it. You won't even notice it happening except for the excess vibration caused. If you're considering putting in longer bolts you'll need to remove the motor mount to access the holes in order to tap them deeper. My advice would be to follow the old adage 'if it ain't broke don't fix it'. Rocket | ||
| Blasterd |
Thanks Rocket, just all the talk had me a little worried. Ken | ||
| M2me |
The same thing happened on my 1992 Sportster. Broke at the exact same spot, so it's not just Buells. I had the head replaced on my Sportster. I didn't know it could be welded. The whole thing including labor was less then $400 if I remember right. These Sportster engines have pretty cheap parts! My 2001 M2 is still okay so far!  | ||
| Rocketman |
 Rocket | ||
| Rocketman |
 Rocket | ||
| Rocketman |
 Rocket | ||
| Rocketman |
 Rocket | ||
| Rocketman |
 Rocket | ||
| Rocketman |
 Rocket | ||
| Rocketman |
 Rocket | ||
| Rocketman |
 Rocket | ||
| Rocketman |
As one can see from the pic's above, the weld needs to be finished by hand for best results. This means with files and wet paper. The finished result will leave a bulge on the visible side of the head. The rear side is not visible once the head is in place on the bike. If memory serves, (it was over two years ago) the bolt is a grade 9 or possibly 10 high tensile strength. The stud dimensions are as follows :- 16mm hex 10mm diameter 76mm overall length 46mm shank 30mm thread depth The spacers I had turned from billet alloy. Their size is as follows :- 27.5mm outside diameter 11.5mm inside diameter 6.5mm width As you can see in the pic, the thread length of 30mm will go all the way into the head casting if you tap the hole all the way with a blind tap. The bolts shank will sit nicely for the motor mount but you will need to use the spacers. I couldn't find a bolt of this strength bearing the the exact dimensions - thus the spacers. Hope this gives some insight as this is a relatively easy and affordable repair with the head removed, and one that probably suits if like me your heads have been flowed by a head tuning guru who now resides in heaven. Good luck. Rocket | ||
| Dynodave |
There are several design problems with the Buell mounting system. After breaking 3 of the stupid things, I had a mount welded from 4 pieces of 1/4" cold rolled STEEL. I tapped the threads in a bit deeper AND got bolts with shanks that extended into the head. The major thing is that STEEL plate. It DONT BREAK and it is THIN, so you don't have 3 feet of bolt being levered around and breaking or ruining the head. Later I got 4-Valve heads. The boss and mount had to be fabbed into this BT head, so (DUHHH!) I MOVED THE RH BOLT TOWARDS THE LH BOLT SO THAT IT WAS SYMMETRIC ABOUT THE HANGER!!! We also went to a fine thread 7/16 bolt (again, DUHHH) | ||
| Mstrfrz |
How much deeper can the hold be tapped? 1/2"? |
