7900 owners headsup

[bwalker]

When running a 8 pin sprocket on a 7900 the saw will leak oil out of the bar groove and it will run down between the bar and the bucking spike. Besides making a mess you get less oil to the tip and to the bottom of the bar. To fix this situation you need to run a chain slightly longer than the standard 72DL chain. I havent tested it yet, but I would think a 74 would work fine.
BTW If you are not running a pin you should try one. It cuts much faster. At least on the 20" and 24" bars I have tried it with.

 

[Jacob J.]

Those pin drive sprockets are harder on the chain which subsequently causes the bar to wear much faster.

 

[bwalker]

JJ, I was using the term 8 pin loosely. The 8 tooth sprocket I have is a Oregon powermate.

 

[Jacob J.]

How is the fix on those oil pumps working out?

 

[bwalker]

How is the fix on those oil pumps working out?

Its held for three days now. Knock on wood.

 

[Stumper]

Ben FYI-thus far I'm having zero problems with oiling running an 8 pin and a 28" bar.

 

[bwalker]

What brand bar, stumper? Mine never did it with a 24" GB, but with 20" windsors and Oregons it does it. As soon as you switch to a 7 tooth sprocket it stops and also cuts much slower. The heal profile of the bar may have something to do with it.
BTW when you are running the saw it full clip, look at the bar rail where it exits the saw body. You will see oil migrating out of this area and runing down the side of the bar or oozing down next to the inside bucking spike.

 

[Jacob J.]

Would opening up the oil inlet hole on the bar help this problem?

 

[bwalker]

Would opening up the oil inlet hole on the bar help this problem?

Windsor bars have a large hole while oregons have a smaller angled hole. The boith do it. The problem is the chain isnt in full contact with the bar around the oiler area due to the increased diameter of the larger sprocket and the fact that with a 72 dl chain the tail of the bar is close to touching the sprocket. Move the bar forward a little and the problem goes away.

 

[Hunter]

Ben,
I have not had any of these problems. I have been running the 8 pin on my 7900 since I first got it. I have not seen the oil ooze from the area you speak of, and please dont think I am saying this does not happen, Just that I have not had this happen to my 7900's. I am running 24"GB bars and 20" Windsor and 36 " windsor. I will see if this happens on any of the new ones I have coming.
I do see what your are talking about, that the larger diameter sprocket has the chain more away at the tail of the bar.

I will have to watch this close. I send most of the saws I sell out with 8 pin sprockets and I dont want to create problems for Customers.Thanks for the headsup.

Thanks
Hunter

 

[Stumper]

Ben. Its an Oregon. PM(s)plus. I'll watch it for the 'drainage' but the chain has been running well oiled.

 

[bwalker]

Stump, As I ams ure you are aware the 7900 puts out copious amounts of oil. You never notice a oiling problem till you see the oil running down the fron of the saw like I described above. When it does this it will still fling oil off the tip.
When the hose fails as I outlined in the other post you lose all oiling.

 

[Dolmar_Tech_Mgr]

Ben, funny you mention the Windsor bar having the problem. I was visiting a Dolmar Wholesalers that was telling me the same problem with a Windsor 20" guide bar. The oil hole was not in the correct spot. I think they said the 20" bar was the only one they experienced this with. I know they contacted Windsor but i do not remember the outcome of that call. Seeing your comment on the Windsor bar sparked my fading memory.

 

[Dolmar_Tech_Mgr]

And when I said the oil hole was not in the correct area, it looked as if (just as you said) the chain did not ride down far enough to pick up the oil out of the bar groove and carry it to the tip.

 

[bwalker]

Its nice to know I am not crazy. I also tried a Oregon Bar and it did it also. Wish i had another brands 20" to try.

 

[Dolmar_Tech_Mgr]

I forwarded this thread to the factory, but I will take to Oregon to see what is going on, We no longer purchase bars from Windsor, but I will talk to them too to find out what i can.

 

[Dolmar_Tech_Mgr]

Talked to a Windsor rep today and discussed the situation with the guide bars discussed in this thread. There were bars producded that when the drive link passes over the oil hole the drive link does not pick up the oil. It is my understanding that they have made the correction to the manufactureing process. Any bars being shipped today will be correct. I dont think there is a way to tell unless you physically slide the chain while looking in the oil hole to see if the drive link is low enough to pick up the oil.