Dolmar 6400 flywheel key dimensions?

[shootingarts]

Ran the Dolkita doing some real work the other day and I can't bring myself to pull that P&C right now. The saw seems to have been a one tree saw, built in 2010 if I am reading the serial number right.

Running premium fuel with no ethanol and I just bought some xylene to start running that at all times to bump octane a little higher. Of course without other changes high octane fuel doesn't make any more go. I plan to tweak timing and compression for now. I know that strictly speaking the flywheel key isn't a must but every time the saw didn't run perfectly I'd be wondering if the timing had moved if I ran it without one. Anybody have a Dolmar flywheel key and measuring tool to give me the dimensions? If you have a crank handy or already know, how much of the key is sticking out the groove above the crank would be great info also as I plan to shape an offset key. I don't see them offered now but the keys with the offset to one side used to be available for some car engines, one way of timing the crank and cam precisely. I'm planning to offset the key about fifty percent, figure that will be a decent starting point unless some feel that is too much advance.

Thanks for any assistance!

Hu

[Andyshine77]

The key is cast into the flywheel, no separate key. You can file on the the key a bit to advance the timing, and if it slips, all it does is go back to stock timing.

Do you know how to degree the engine? Bumping the octane is pointless, and unless you're a chemist or have experience mixing race fuels, you could damage the saw. The compression on stock Dolmar's is normally pretty good, so unless you're going to port the saw you may be wasting your time. 

[shootingarts]

Andre,

As not knowing the key was cast into the flywheel on the Dolmar indicates, I don't know much about saw engines and two cycle engines in general. High performance cars I was once pretty comfortable with. Built complete cars for circle track racing back when the world was young, including engines. I have mixed fuel many times, not something to be careless with especially when messing with oxygen bearing additives. However xylene is in pretty much any gasoline, probably any gasoline but I don't want to make a blanket statement.

Degree wheels and such I am very familiar with, proper install of a camshaft demands it and tuning the relationship between the camshaft and crank on engines that have both is a great way to fine tune a camshaft to a particular set-up; vehicle weight and use, the other components used in the engine, the track you are on that week or that night. Of course changing crank/cam timing that often requires a set-up that makes it easy. We used to use offset bushings when running gear driven camshafts way back when and shop made two piece timing assembly covers.

Some health issues have limited me to a few minutes running the saw here and there and no standing at the lathe doing work for over a month, bored out of my skin and looking for something to get into as much as anything else. While the timing retarding a little bit back to the standard setting wouldn't harm anything other than perhaps performance a little, I'm not as keen about cutting on a flywheel. Thank you for the information, saves me wasting time meddling in that direction.

Now about compression . . . .    ;D

Hu

[Andyshine77]

Yes sir xylene is in most fuel today. I was just trying to get an idea of you're knowledge, seems you've been around the block once or twice.

Filing on the cast key is quite normal when porting chainsaws, there is nothing wrong with it whatsoever. The 7900's like 4° to 6° advance. Filing the key works well because, and like I said you can always go back to stock timing if you don't like the way the engine runs, hard starting, kickback and so on.

Compression?? Well the Dolmer 7900's love compression, but too much and you could trash the bottom end. The Solo 681's were notorious for the cranks twisting out of phase. The pin on the 7900 is stronger, so it's not as much of a concern. We are talking about the 6400/7900's?

[shootingarts]

This is the Makita 6401, made by Dolmar in 2010 according to the serial number and the information I found on the net. Don't know if the "07" before the two digits indicating year indicate the month of manufacture or not. My understanding is that this saw is identical to the 6400 Dolmar other than the dye in the plastic. It had a Dolmar chain on it when I got it, that seemed to be rebranded 92 Vanguard best I remember at the moment.

Famous last words but this crank should be able to handle raising compression when it is just over the surface area of the smaller 6400 piston. Suspect that I will eventually make a 7900 out of it but of course with a new piston and cylinder I'll be setting up compression all over again too. I'm not going to get too silly anyhow, this is my only saw other than a toy. Got to use it as a work saw a few times a week if not daily when I am up to working, my cookie cutting is pretty much limited to cutting painted ends off of logs so whatever is painted on them doesn't get airborne either from the lathe or in a fire. 

Hu

[Andyshine77]

Yes they're the same saws. Makita owns Dolmar and has for some time now. I currently have 5 Dolmar saw and a few are ported. Get some Stihl RS chain, you'll love it.

You can push compression up to 210 on this series saw without any issues. You can set squish to .018" to .020"

Here is a video of my ported 7900 with a 32" B&C cutting some very hard Beech.

http://youtu.be/jjriW-powdg

   

[shootingarts]

I couldn't see the video in your post so I just went to your youtube channel and looked around. Saw the 7900 and other nice toys! (revisit that, it wouldn't come up in your post at first, saw the video was visible when I was verifying info while typing my post. Very nice, doesn't do anything to ease my 7900 itch though!)

Maybe I'll stumble on one of the old Home Depot saws or something to put the 7900 top end on or one day the itch might be too strong and I'll put the 7900 top end on this one. The RS chain is what shut down my big bore project for awhile. Bought a couple loops last week at the Stihl dealer and ran one in some dried cherry and oak logs a couple days ago. You are absolutely right, love the RS chain, I'd be perfectly happy with the saw if it never cut any better than it does now with the RS chain. I want more but I'm very impressed with the saw as it is. I had pretty high hopes for this saw and it seems to be meeting them easily. The ported 7900 like you have would be the Boss Hoss in the woods around here!

Hu

[Andyshine77]

That video is on a friends YouTube account, but that's me in the video. You can visit my YouTube by clicking on the link under my avatar, if you haven't already.

The 6401/6400 is a fine saw as is. Even though it has less displacement than the 7900, it has the same stroke.

[shootingarts]

That video is on a friends YouTube account, but that's me in the video. You can visit my YouTube by clicking on the link under my avatar, if you haven't already.

The 6401/6400 is a fine saw as is. Even though it has less displacement than the 7900, it has the same stroke.

I did bookmark your video's for future  viewing when I'm up late night. I'm far enough in the country that I have to run satellite to have internet. They give me limited monthly usage but unmetered from midnight to five AM so that is when I watch most video.

I agree it's a nice saw. The biggest complaint I have seen about the saw is it's weight for it's displacement. I don't know about that but it's weight for how it cuts seems just fine. I was very less than impressed with the factory chain on it but it woke up in a hurry with the RS on the bar. I suspect some of the moaning comes from people that are running less aggressive chain. Twenty inch bar on my saw right now and I was wondering if the full comp chain was going to work OK noodling cutting bowl blanks. Very well pleased so far!

Hu

[Andyshine77]

A 20" bar is nothing for a 6400, I've seen them run a 28" bar cutting a big stump, and it did really well.