Valve Adjustment - Shimming nightmare - Any ideas?

[angusec]

Hi all, I'm working through my first valve adjustment with the RC. Second owner and the original didn't have anything for records so I'm going to assume never had valves checked (12,000km). After pulling everything apart I was tight on all 4 valves by either .01 or .02mm, not a big deal. So I picked up the Wiseco shim kit and using basic math (yes, I verified each shim with calipers and then a friends set of calipers) I dropped each shim 0.05mm. Simple right? Well, after reassembly, I had only 1 valve in-spec.

Conveniently, my licensed mechanic pal showed up, and going through it he was as baffled as I was. So dropping the remaining 3 another 0.05mm, one more came into spec. Completing the disassembly/reassembly again and dropping another 0.05mm I'm still tight on my LI and RE (AFTER GETTING MY 0.05mm through both instances then dropping the corresponding shim 0.10mm - this makes no sense, I know).

So when I inevitably get back to it, I was curious if anyone else has had these mind-bending issue? Or theres something I could be glaringly messing up. The next adjustment to chase the LI and RE valves will have me having dropped 0.15mm which is a lot more than I've ever had to do for any other bikes shims.

Key point/question: the Wiseco shims do not have a taper on the edge that the OEM shims have and I'm wondering if it slightly changes where the arm sits

My mechanic pal suggested to just start at 2.10mm-2.20mm (my intake starting points were 2.50mm and exhaust both 2.60mm) and build up from there.

Any one else with similar head-smashing inducing tales? If so, how did you come to make your headway?

Thanks,
Angus

 

[cjwell]

I suspect the non radius shims are sitting on the retainer and not on valve stem. With that said I also suspect the keepers and retainers are beat up/sheering top notch. I have seen that happen twice, they were both moments away form dropping valve(s). The top notch on the keeper was almost totally gone. That allows the retainer to slide way up the stem too far and not let the shim sit on the valve stem. I would use some grease on the stem end, very thin amount, sit shim in and see if it touches the grease. If not you know it's resting on the retainer. DO NOT run it like that, it will drop one in no time. You will probably be pulling head off and disassembling/replacing valves, springs, retainer, keepers. They sell a whole kit that includes all the valve components. Somewhere on here I've posted pictures of beat up keepers....

 

[Formula390]

I was thinking the same thing Chad wrote as I read the original posting that it sounds like the keepers / retainers are the problem. Neat trick posted by Chad to check for the shim/stem contact. It's gonna be a little tricky with the motor in the frame, but that would certainly tell you if you've got a problem with the valve/keepers/retainers or not.

 

[angusec]

What components would wear first if this was the case? Obviously it makes most sense to replace all, but I already have the Gray retainers (uninstalled) and wondering if its plausible to expect to only replace the keepers or if the valve stems would become marked up and need replacing?

Doubt any serious valve work can happen without dropping the engine, safe bet?

 

[cjwell]

Engine has to come out to pull head. Typically just the keepers are worn/sheering. BUT for the price of new valves "I" would replace them too. The retainers are not the only problem....

 

[BlueFlag]

I stumbled upon a same issue with my engine. I was running a bit tight on the left exhaust valve so I changed the shim for thinner OEM KTM replacement shim which did’t have tapered edge (the old one did) and the clearance lowered. After reading this thread I suspected the new shim was sitting on the retainer. So, to test it, I tapered the edge on the new shim and put it back in. The clearance was now as it’s supposed to be.
Now I plan on changing the retainer and keepers. Do you think it will solve the issue or someone has a better idea?

 

[BlueFlag]

So, I report back after I replaced the keepers and retainers (also on the second exhaust valve as a precaution). At first I was worried because I couldn’t see any obvious wear on the old keepers and retainers but after I put the new in, it was apparent that the shim was sitting higher relative to the top of the retainer than when the old ones were in. Now the clearance is same with tapered or non tapered shim.