Dolmar 5105 Rev Limiter

[blsnelling]

It's been discussed many times here that the rev limiter on a saw can be mistaken as 4-stroking. One solution is to tune with a tachometer. I put a tach on a ported 5105 this evening and found that it does not bounce and go crazy when you hit the limiter, like limited saws traditionally do. It would be entirely possible to go way too lean and still be getting what appears to be a valid tach reading. The solution for a stock saw is to go fat and come up to the RPM you're shooting for. As always, the only way to tune a ported saw with a limited coil, is in the wood. Don't burn your 5105 up guys!

BTW. the coil maxed out at 14,200, still 4-stroking hard since it's ported.

 

[J.W Younger]

It's been discussed many times here that the rev limiter on a saw can be mistaken as 4-stroking. One solution is to tune with a tachometer. I put a tach on a ported 5105 this evening and found that it does not bounce and go crazy when you hit the limiter, like limited saws traditionally do. It would be entirely possible to go way too lean and still be getting what appears to be a valid tach reading. The solution for a stock saw is to go fat and come up to the RPM you're shooting for. As always, the only way to tune a ported saw with a limited coil, is in the wood. Don't burn your 5105 up guys!

BTW. the coil maxed out at 14,200, still 4-stroking hard since it's ported.

Thats good info-did it sound real ragged when it reached the limiter?

 

[blsnelling]

No. Remember this is a ported saw, so would likely turn 15,000-15,500.

 

[JustinM]

really good info, Brad. Thanks

 

[166]

The 5105 with the regular recoil has a coil rev limited to 14,500 RPM. The newest 5105 with Easy Start is Rev limited to 13,800. The Easy Start 5105 will not accept the 14,500 coil because if a different crankshaft.

So if you're looking to port a 5105 you're better off without the easy start.

 

[Andyshine77]

I'd like to add that I find it harder to tune strato saws with a tack as well. I find them harder to tune in general, as they sound and behave much differently than a normal two stroke saw. I actually almost had the H needle seated, and it still sounded OK at WOT, and the rpm's were still within spec. One more thing I observed is the saw will act like it's starving for fuel if you set the H too rich. I believe this has to do with a balance of pressures between the fresh air and incoming charge. If you go too far one way or the other the balance gets out of sync.

 

[Fastcast]

The solution for a stock saw is to go fat and come up to the RPM you're shooting for.

This is the way I tune my saws, 5100s included....No need for a tach like this and haven't burned one up yet.

Is there more left, maybe a little but I'm not racing, just cutting wood so they run good enough for me and stay ready to work for the next time out.

 

[blsnelling]

This is the way I tune my saws, 5100s included....No need for a tach like this and haven't burned one up yet.

Is there more left, maybe a little but I'm not racing, just cutting wood so they run good enough for me and stay ready to work for the next time out.

Yup. It's obvious when it's fat and the RPMs are below the limiter. Slowly turn the H in until the RPMs max. Back it up a hair to be on the safe side.

 

[RTK]

Is there any possible way to disable the limiter?? Or find some replacement coil??