Changed Starter Clutch Now Bike Just Backfires and Won't Run

Untitled by vfrMatt86 posted Aug 4, 2021 at 3:44 PM

I had the infamous crunchy starter issue. I took it all apart and found that that starter clutch was in multiple pieces.

I took pictures of everything, noting the orientation and re-assembled it all exactly as I took it apart.

Now the bike turns over cleanly without any awful sounds but she just backfires and won't run.

I'm assuming the timing on these bikes is fixed.

Any one have any ideas or any threads I can start pulling to sort this? Bike ran perfectly fine before I parked it 3 weeks ago to drop the oil and investigate the starter clutch.

 

If its like the VF1000R, There is an alignment mark on the starter clutch that has to be lined up with the crank I believe. Been a while so I dont recall the details, but id guess that may be your issue.

 

I didn't see any marks but the splined shaft from the crank has a wide groove on it that aligns with a wide groove on the start clutch assembly. That can only go on one way.

She sat for 3 weeks off the tender so I'm currently charging the battery to eliminate any low battery issues. I've also purchased a set of new plugs that'll be here tomorrow in case that's the issue.

I guess worst case scenario I drain the oil again and tear it all apart. I'm just confused as to what I could have done wrong.

 

ok, different the VF1kR then. my buddy had a similar issue with his VF1KR and he hadn't aligned the timing marks on the starter clutch with the crank. seems the VFR750 is a different setup.

with the way the starter clutch mounts with the "wide groove" of the spline shaft, there is no way it could be 180 degrees out then ?

Im sure Captain 80's will check in with some ideas.

 

didn't say where you got the replacement, could be for a similar but different bike ?

 

*deep sigh*

Yea... I just put that together myself but hadn't had a chance to update the thread. The existing clutch looked like the first pic but the clutch I was shipped looked like the 2nd.

So that was $250 of money I should have thrown at strippers.

I'll order another clutch that's the correct part. The original starter clutch is part no: 28120-ML7-000 While the replacement I got was part no: 28120-ML7-690

At the time I thought it was an updated part. I see now that I was wrong.

I do have a 96 vfr 750 that will likely need this part at some point so it's not a complete loss and I can rest easy knowing that I didn't install it improperly.

 

Well it appears that the part is discontinued. I've created a WTB thread about this part.

Here is the link: https://vfrworld.com/threads/help-need-86-vfr-750-starter-clutch-its-discontinued.59623/

 

So.. in the event that I can't find one.

A couple solutions that come to mind for me are...

1. Buy a new (28120-ML7-690) starter clutch.. then figure out a way to separate the outer housing from the center hub. Perhaps the steel would expand faster thus allowing me to remove it?

2. Buy a 28120-ML7-690 starter clutch and grind down all the pulse trigger tabs. Then create a weld bead in the same position, height and length as the 28120-ML7-000

3. Weld the cracks in my broken 28120-ML7-000 starter clutch. Anyone know what kind of metal the cracked center hub is?

Has anyone had and solved this problem already?

 

1: Maybe try and find the cheapest used one of the newer style and start experimenting on it.

I like #2. But I would probably create them ahead of time, have them welded on, and grind as needed. You might be able to bond them, but I don't know how confident I would be in the long run.

3: I have read reports of people having them welded with success, but I don't remember reading about any long term conclusive follow ups.

 

I can't imagine loose welds bouncing around in there would be a good thing.

 

Flea Bay may be your best bet. I recently got a starter clutch for my "new to me" 84 CBX750, they're few and far between for the CBX750 and I still found one, but I imagine you'd find a decent used one on the Bay.

 

By now I suspect a fair few 750s have visited the wrong side of a hedge and are now in breakers yards being slowly stipped of bits. Sadly you may be at the stage where rather than just searching for that specific part you should perhaps search for a breakers yard with an identical wrecked bike to use as a long term spare parts source.

 

I’ve used stitching for a crankcase repair on a 2 stroke triple and it worked a treat, it’d be worth your time to investigate

Like this https://www.metalockengineering.com/en/typical-repairs/metal-stitching/