Pointers for a "Big Bore" kit ala DCS-6401 Upgrade to 84cc

[Brewmaster]

I picked up a medium good shape DCS-6401 for $120 and am going to take it upward in life ... to an 84cc stud.

Suggestions for the process?
Carb seems ok ... don't want to mess with it just yet.

Any pointers for break-in or "don't forget" ... or "this is a good time to ..."




I think I am done saw swapping for a bit.

Ending up with:

1. a DCS-510 18" "like new"
2. a Husqvarna 435 16" "like new"
3. and a DCS-6401 w/new jug and piston to 84cc with new 30" bar and new 20" bar.

Swapped out enough gear so these are free.


Might try to swap out the Husqvarna 435 to get a Husky T435 or 338XPT

Thoughts on these two?

 

[pops21]

Yeah...... Get ready to have a rude awakening in the difference in power when your done. 64cc's to 84cc's is a rather large jump. That saw will laugh at a 30" bar.

I'm not sure if the oiler can handle a larger bar then what the 6401 was ment to pull. Maybe some one else can shed some light on that matter. I think the only difference between the 6401 and 7900 is piston and cylinder. If that is the case then your good to go.

 

[redunshee]

Yeah...... Get ready to have a rude awakening in the difference in power when your done. 64cc's to 84cc's is a rather large jump. That saw will laugh at a 30" bar.

I'm not sure if the oiler can handle a larger bar then what the 6401 was ment to pull. Maybe some one else can shed some light on that matter. I think the only difference between the 6401 and 7900 is piston and cylinder. If that is the case then your good to go.

Yea, believe its simply a P and C change. Baileys has them for sale.

 

[rmihalek]

Brewmaster, I did the same swap a few months ago. I seem to remember that the clearance between the carburetor flange and the saw housing is kind of tight. You may want to do a loose-fit installation of the cylinder (slip it down over the ring-less piston) and see what kind of clearance you have. If it's tight, then you may want to install the carb boot first before doing the final cylinder installation.

Other than that, everything went smoothly. I've only run a couple tanks of fuel through the saw so far and it is still getting stronger. Just this last weekend I noticed it was revving out a bit too much, so I had to back the H jet out a 1/4 turn to get it to 4-stroke at WOT.

It's a monster in the wood. I was noodling some rock maple firewood rounds with round ground chain and 8 tooth sprocket on a 20 inch bar. It really moves through the wood with this combo.

Here's a look at the clearance:

 

[roncoinc]

https://www.baileysonline.com/itemdetail.asp?item=BBN 7900

I picked up a medium good shape DCS-6401 for $120 and am going to take it upward in life ... to an 84cc stud.

Suggestions for the process?
Carb seems ok ... don't want to mess with it just yet.

Any pointers for break-in or "don't forget" ... or "this is a good time to ..."

I posted a build on this awhile back with lots of pix.
try search.

 

[Brewmaster]

https://www.baileysonline.com/itemdetail.asp?item=BBN 7900

I picked up a medium good shape DCS-6401 for $120 and am going to take it upward in life ... to an 84cc stud.

Suggestions for the process?
Carb seems ok ... don't want to mess with it just yet.

Any pointers for break-in or "don't forget" ... or "this is a good time to ..."

I posted a build on this awhile back with lots of pix.
try search.

Thanks man ... after digging a bit ... I found it !!!


http://www.arboristsite.com/showthread.php?t=138986&highlight=dcs6401


Thanks again !!!

 

[T_F_E]

I have a thread to, its a really easy swap, spend a minute with a dremel when you have the carb out and cut the tips off the limiter caps. I needed about 1/8 turn richer. Other than that it is really simple and should take you less than 2 hours. You can do they whole thing with the factory tools included with the saw haha.

And the oiler on the 7900 is the same as the 6400 so you can pull a 36" bar I think it is.

 

[Grande Dog]

Howdy,
It's always good to get a pressure/vac test before and after.
Regards
Gregg

 

[madhatte]

Try to get a base adjustment on the carb BEFORE puttinng the cover plate over the intake -- you can't see the screws otherwise, and it's easy to miss the screws and release the throttle cable with your screwdriver. After that you shouldn't have to mess with it too much... at least, I haven't. I haven't had oiler problems, either, and have milled with up to a 36" bar in PNW softwoods.

 

[mowoodchopper]

Pointers, Get a Dolmar 7900 kit and forget the bigbore!

 

[Brewmaster]

Pointers, Get a Dolmar 7900 kit and forget the bigbore!

Where would the fun in that be?

 

[mowoodchopper]

Where would the fun in that be?

Trust me ! Its alot more fun to put the oem kit on and watch how badass your saw is, than it is to run the aftermarket bb and tear it back down again to try dig all the little pieces of piston out of the crank case!

 

[roncoinc]

Trust me ! Its alot more fun to put the oem kit on and watch how badass your saw is, than it is to run the aftermarket bb and tear it back down again to try dig all the little pieces of piston out of the crank case!

Interesting,i have never heard of that happening ...
did i miss the post on that ??

 

[mtngun]

Interesting,i have never heard of that happening ...
did i miss the post on that ??

There have been a couple of piston failures on some of the other BB kits (044, 066) that were highly modded. I don't recall seeing a thread about a piston failure on a stock BB kit.

I've got a 'kita project in the works, and will be considering the BB kit. If there is a problem, you know Grande Dog will make it right.

 

[mowoodchopper]

you guys must live under a rock! READ!!!!!!!!!!!!!!!!!!!!!

 

[mtngun]

you guys must live under a rock! READ!!!!!!!!!!!!!!!!!!!!!

Link ?

 

[mowoodchopper]

link ?

search!

 

[rmihalek]

I just searched using a variety of different terms (big bore failure, makita BB, dolmar BB, big bore problems, etc.) and only found some vague references to plating that may chip off when porting. No pictures of chipped plating resulting from porting were found. No reports of big bore failures such as you claimed (piston grenading) were found.

I'm not saying that this was a 100% complete search, but if there are reports of failures, I couldn't find them using some obvious search terms.

 

[atlarge54]

I just searched using a variety of different terms (big bore failure, makita BB, dolmar BB, big bore problems, etc.) and only found some vague references to plating that may chip off when porting. No pictures of chipped plating resulting from porting were found. No reports of big bore failures such as you claimed (piston grenading) were found.

I'm not saying that this was a 100% complete search, but if there are reports of failures, I couldn't find them using some obvious search terms.

Did you try the advanced search featue? The normal search feature leaves a lot to be desired.

 

[mtngun]

search!

I think the person making the claim should be responsible for backing up his claim.