Jonsered 2150 cheap build and mod

[modder]

I picked up a couple 2005 Jonsered 2150's that run but need a bit of work, so I decided to tear one down and do an economy build and port job. I found an old thread from a few years back that bsnelling had started about porting a Husqvarna 350 and was inspired. He posted a few good pic's of his port job that I plan to use as reference and I'll add a couple of my own twists. Since I need to tear one of the 2150's down to swap out the body for a spare I had sitting around, I thought I'd see what kind of gains I can get with an amature port job. I got it stripped down and started the mods and porting today. I plan on using a walbro 199 from a 357xp and will see if it works better than the zama from the 357. I didn't get the 353 piston yet but some will be glad to hear Meteor now sells an aftermarket 353 piston. I noticed that bsnelling had to use one from a 51 husky instead. The P&C are in great shape and compression felt very good so I'm going to use the originals for now. I shaved 1mm from the top of the factory dish top piston, and 1.5mm from the riser to increase compression a bit for now. I will also be tossing the base gasket so I will need to check my squish again, but it should be ok. I have also smoothed out the flow on the riser and removed the transfer dividers on it in an attempt to promote better flow. I haven't heard of anyone doing port work to the riser before (as in removing the transfer dividers and smoothing things out) but thought I'd try it and see what happens. I will post some pic's soon and more as I go if anyone is interested in seeing an amature at work. I picked up a muffler from a 2149 because this saw didn't have one when I bought it. The guy said he lost it and it is obvious that he was running it while loose as it melted the plastics. That is the reason for the body swap. The 2149 muffler is completely hollow so it will be a bit easier to mod, and I'm going to add another port beside the existing one. I already goofed up on one of the transfer covers by grinding a bit too far so I used some JB weld to seal the small hole and I'll smooth it out again, after it hardens. I have a spare one if the JB weld doesn't hold. If anyone would like to throw in some tips or warnings, I would appreciate it and my ears are open.

 

[old-cat]

I was already warned by one the the top builders here, that JB weld is risky if there's any chance at all for it to reach the internals.

 

[moody]

What do think removing the dividers has to offer you?

 

[modder]

I may try brazing it then. I don't want to start grinding my spare cap in case I make the same mistake.

 

[modder]

What do think removing the dividers has to offer you?

I thought it may give a bit more unobstructed flow but I'm not sure if it will do anything at all. I wanted to try something new to see what the outcome is. Do you think it will have a negative effect. I have a spare riser so, if it makes it run poorly, I'll just swap it out.

 

[moody]

I thought it may give a bit more unobstructed flow but I'm not sure if it will do anything at all. I wanted to try something new to see what the outcome is. Do you think it will have a negative effect. I have a spare riser so, if it makes it run poorly, I'll just swap it out.

It's going to increase crank case volume so everything else you do will dictate how it pans out.

 

[wcorey]

I may try brazing it then.

Welding aluminum with oxy/acetylene is pretty tricky if you haven't done it before.
JB weld will probably work fine if its in a confined area like a corner or a surface that gets bolted down against another surface.
I think it's questionable gas resistance may be the biggest issue.

I wanted to try something new to see what the outcome is.

I think I'm missing something here.

How are you going to know if it's an improvement unless you try it with the divider and then without?
Some of the divider is on the cylinder, so you'd have to swap out the whole top end to see the difference,
so the porting on each cylinder would then need to be otherwise identical. Not easy...
I find it's usually easier to do incremental changes starting with the un-modded parts rather than the other way around.

 

[moody]

Quad ports run better for a reason. But this would be a way for him to learn that.

 

[nmurph]

...I shaved 1mm from the top of the factory dish top piston, and 1.5mm from the riser to increase compression a bit for now. I will also be tossing the base gasket so I will need to check my squish again, but it should be ok...

:msp_w00t::msp_w00t::msp_w00t:

I hope so since you have already done it. You should have taken some measurements bf you start.

 

[srcarr52]

Epoxy over the top of the transfer caps is fine. If it pops off you'll recognize it quickly. I prefer to use Devcon F, JB weld is really a crappy epoxy for aluminum.

 

[modder]

Welding aluminum with oxy/acetylene is pretty tricky if you haven't done it before.
JB weld will probably work fine if its in a confined area like a corner or a surface that gets bolted down against another surface.
I think it's questionable gas resistance may be the biggest issue.


I just went out and fixed the tiny hole. #I didn't really braze it. I have aluminum brazing-welding rods that work with MAP gas and it came out really good. #I welded it from both sides then cleaned it up and it looks really good.#



I think I'm missing something here.

How are you going to know if it's an improvement unless you try it with the divider and then without?
Some of the divider is on the cylinder, so you'd have to swap out the whole top end to see the difference,
so the porting on each cylinder would then need to be otherwise identical. Not easy...
I find it's usually easier to do incremental changes starting with the un-modded parts rather than the other way around.

I don't think the changes to the divider would make any gains without continuing the porting into the cylinder. I have tried the saw stock, and I still have another complete saw that is all stock to compare it to when I'm done. There isn't a divider on the cylinder on these ones until half way up the transfers and its small and doesn't continue the rest of the way up and then divides again before it goes into the combustion chamber. I removed the divider in the transfers also, just like blsnelling did on his 350, but I don't believe he removed the ones on the riser. That's why I curious to see what it will do. I am going to port the transfers, widen the exhaust, and intake also. I know I,m doing a lot at once, but this is just a cheap way of practicing and playing at the same time. I'm sure along the way, I will do several things that people will slam me for.

 

[modder]

:msp_w00t::msp_w00t::msp_w00t:

I hope so since you have already done it. You should have taken some measurements bf you start.

Sure did, but I have several different gauge gasket material and will make my own gasket if I need to adjust the squish wider than it is now, or I may just shave a bit more off the top edges of the piston. I know just enough to be dangerous.:msp_biggrin: I know you guys hate to see someone ruin a good jug, but I don't really have much to loose and if I mess it all up, its a great excuse to get a 346 top end.


Moody,
It will still be quad port as I am leaving the divider to the combustion chamber, but I am going to widen the ports and reshape the transition of the divider. It just doesn't make sense to me when the divider is intermittent like it comes from factory. It starts at the riser, then its open until half way up the transfers, then there is a crude, two piece divider, then open, then another divider to the combustion chamber. I understand how the xp transfers can work better, but they are completely separate all the way up and have a smooth shape. The way the 2150 cylinders come, they are hardly better than open port. I'm still learning, and this is part of my process.

 

[moody]

it makes perfect sense the way it comes out of the box. It works for what it was designed for. Removing won't gain you anything. But go ahead and test it out. Removing it affects a couple things.

Case volume
Charge velocity
And you're losing charge direction

 

[modder]

it makes perfect sense the way it comes out of the box. It works for what it was designed for. Removing won't gain you anything. But go ahead and test it out. Removing it affects a couple things.

Case volume
Charge velocity
And you're losing charge direction

I agree there will be major changes to how it works and you could be completely right but the only thing I have to loose is time. The only thing I am doing different than other builders that had great gains is the riser, and I can easily swap it out if it doesn't produce enough charge velocity. There have been a few on this site that got rid of the center transfer divider and they turned out well. I thought I would need more volume for the saw to be able to accept the larger carb and smoothing it out would help it maintain velocity. Again, you are likely right, and time will tell.

For those interested, here are a few pics.
The first pic is the original melted body, second is the donor, and third is the risers.View attachment 312892View attachment 312893View attachment 312894

 

[moody]

Any updates yet?

 

[john_bud]

it makes perfect sense the way it comes out of the box. It works for what it was designed for. Removing won't gain you anything. But go ahead and test it out. Removing it affects a couple things.

Case volume
Charge velocity
And you're losing charge direction

Those 3 things help determine the amount of charge mixing in the cylinder and the charge tumble. those things are needed to get uniform complete combustion. flame front dynamics are an incredibly complex phenomenon. Sadly, even with today's software and massive computing power, trial and error are still needed to fine tune to perfection. The OP may find some power... or not. I for one sure don't know, but am excited to be able to watch and learn!


I applaud the OP for attempting this and especially for posting up here. Also, great round of applause for the open minded way he is taking the comments. That's VERY hard to do .

 

[moody]

Those 3 things help determine the amount of charge mixing in the cylinder and the charge tumble. those things are needed to get uniform complete combustion. flame front dynamics are an incredibly complex phenomenon. Sadly, even with today's software and massive computing power, trial and error are still needed to fine tune to perfection. The OP may find some power... or not. I for one sure don't know, but am excited to be able to watch and learn!


I applaud the OP for attempting this and especially for posting up here. Also, great round of applause for the open minded way he is taking the comments. That's VERY hard to do .

I'm all for him trying and it's a good thing to be open minded. Although I doubt that gains will be had by doing this I'm all for him trying. He just needs to be mindful of his numbers and how everything he decides to do will affect his findings.

IMHO the OP should try the riser both ways stock. It'll be easier to find out if he's going in the right direction. The best way to try new things is to keep everything consistent to help find gains. The more variables you add the less likely you are to find solid proof of gains or losses

 

[tolman_paul]

As mentioned you may find the mods are not advantageous.

Typically we often conentrate on the transfer ports function to admit a fresh charge of fuel and air into the cylinder, but neglect to give proper heed to the role of transfers function to scavenge the exhaust gasses out of the cylinder as well as limiting the amount of fresh fuel and air from short circuiting out the exhaust.

You'll probably discover that the modifications will hurt your idle and mid-range power for a questionable gain on the top end. Effectively what you've done is reduce the velocity of the charge by increasing the port area as well as reducing the charge velocity by increasing the crankcase volume.

 

[john_bud]

The best way to try new things is to keep everything consistent to help find gains. The more variables you add the less likely you are to find solid proof of gains or losses

Spoken like a true scientist!

It's especially hard to verify gains when there are many variables with the test of the gain. Its one reason I only MM and twirl the little orange screwdriver!

 

[modder]

I didn't get a chance to play with it since my last post but hope to tomorrow. I think I'm going to keep a bit more of the upper divider in the transfers but just do some re-shaping to promote better flow into the transfer ports. I was given a good spare cylinder by the local dealer incase things go very wrong. I have a spare, untouched riser that I can swap back to see the true influance the changes have made. My thinking was that I would need more crank case volume to be able to accept the additional fuel and air the larger 199 hda carb will be providing. The larger intake, case volume, and transfers would allow that air and fuel to get into the combustion chamber, and larger exhaust port and muffler mod will allow those extra gasses to escape. No matter how much more fuel you try to put in, there would still only be so much room in the crank case fo fit it until you run out of room when it is stock. It makes sense in my head. Let's see how it works in reality. I promis I will learn something and I'm sure others will also