MS290 Rebuild Questions

[Fog1965]

Thanks to the EPA and a less than honest dealer, I now get to rebuild my MS290. But, I have a few questions about these engines. My background in 2 cycles is over 30 years of high performance racing engines. They operate at higher rpms - 28,000-29,000 compared to the 12,000-14,000 of my 290. They also run on nitromethene, methonal, and oil and not gasoline/oil and produce about 32 hp/cubic inch instead of the 1.x hp/ci of my 290. Basically the same thing as a chainsaw engine only different. But the construction of the "case" is not what I am used to.

In looking at the IPL and service manual, I have a few questions which I am sure a number of people have already come across or know. From looking through the forum, I doubt that there is anything that someone here has not tried or done.

The lean EPA settings combined with the "Intelli-carb" and ethanol in the gas killed the piston cylinder assembly, so I needed a new jug and piston. Doing google searches I found a new long block for an MS290. Price looked good at $160, cheaper than a new piston/cylinder from a Stihl dealer. I just got it in the mail today, but have some questions. It has both Stihl and Mahle on the cylider. Also the part number does not match that of an MS290 or 029. It has 1127-029, while the IPL has 1127-20-1213 or 1216. This jug also has 46ZD11 on it, which I could not find. The case pan also has 1127-021-2560 A while the IPL has 1127-021-2500, so I don't know if it is a later version or not. The finish on the cylinder is duller than what I can see on mine right now. I have not taken my saw apart yet. Basiclly I am not sure what this part is, if it is really a new MS290 engine or something else - all I really know is it is all the parts are new (cylinder, piston, pan, crank, rod, bearings and seals). I plan on rebuilding the engine that is currently in the saw, maybe putting a 390 piston/cylinder on it or getting the dead one bored .120 and replated, when I get some more money. In racing you always had two of everything, except engines - I took 6 with me to a race.

The pan does not contact the cylinder assembly, there is a gap of around 1/32". I cannot push the two parts together by hand and don't want to force something. Are they designed this way to create a "crush" on the bearings to hold them in place when the bolts are tightened down. There was no mention of this in the service manual.

I plan on adjusting the carb from the factory settings to what it should be. My race engines were always set a slight bit rich, so I intend to do the same on my saw. I would also like to eliminate the "Intelli-carb" leaning out the mixture. I would just as soon have the engine go richer instead of burning down to tell me the filter needs cleaning. If there is a better carb, or some recommendation for changes to this one - I am open to that.

And lastly, my plans are to dump the Stihl oil - since I have no idea of its specs and go to Klotz KL200. That is the same oil I used in my race engines that take a lot more abuse than my chainsaw. Any experience on that oil in a chainsaw would be welcome as well. I plan on running 5% (19:1) since the ethanol can be as much as 15% in the Houston area now.

Any information will be welcome.
Thanks in advance,
Fog Tanner

 

[sefh3]

Read this thread it will help you while tearing that saw down.

 

[Saw Dr.]

Fog1965..... Where to start.....

You are in luck, this is the right place to come for all your answers. Most here don't like 290's. I like them because I have had good luck selling rebuilt ones. Luckily, I am stuck in CVG airport for 4.5 hours with nothing to do and free internet. I will address your post a piece at a time.

Thanks to the EPA and a less than honest dealer, I now get to rebuild my MS290. But, I have a few questions about these engines. My background in 2 cycles is over 30 years of high performance racing engines. They operate at higher rpms - 28,000-29,000 compared to the 12,000-14,000 of my 290. They also run on nitromethene, methonal, and oil and not gasoline/oil and produce about 32 hp/cubic inch instead of the 1.x hp/ci of my 290. Basically the same thing as a chainsaw engine only different. But the construction of the "case" is not what I am used to.

In looking at the IPL and service manual, I have a few questions which I am sure a number of people have already come across or know. From looking through the forum, I doubt that there is anything that someone here has not tried or done.

It was not the EPA that killed your 290. Unless the carb screws are all the way counterclockwise against the stops, it was your dealer's lack of setting it up right that killed it. The clamshell design of the 290 has been around for MANY years. Sadly, that is probably the way alot of OPE will go in the coming years. Maybe not as easy to rebuild, but with proper care they don't need rebuilt often at all.

The lean EPA settings combined with the "Intelli-carb" and ethanol in the gas killed the piston cylinder assembly, so I needed a new jug and piston.

Unfortunately, you may have bought parts you did not need. There is plenty to read on here about cleaning up scored cylinders. I have had better than 50/50 odds at cleaning up scored 290 cylinders. You may have gotten away with a cylinder cleanup, and a $30 meteor piston to get it back into service. Moot point now, though.

Doing google searches I found a new long block for an MS290. Price looked good at $160, cheaper than a new piston/cylinder from a Stihl dealer. I just got it in the mail today, but have some questions. It has both Stihl and Mahle on the cylider. Also the part number does not match that of an MS290 or 029. It has 1127-029, while the IPL has 1127-20-1213 or 1216. This jug also has 46ZD11 on it, which I could not find. The case pan also has 1127-021-2560 A while the IPL has 1127-021-2500, so I don't know if it is a later version or not. The finish on the cylinder is duller than what I can see on mine right now. I have not taken my saw apart yet. Basiclly I am not sure what this part is, if it is really a new MS290 engine or something else - all I really know is it is all the parts are new (cylinder, piston, pan, crank, rod, bearings and seals).

You have the latest engine iteration. From time to time, Stihl makes slight changes to the porting or other things on those cylinders. I think there are about 5 different versions of that one in the 46mm bore. They all are interchangeable. Search "1127 cylinder thread" if you care. I'll be updating that one soon with some 45mm cylinder pics. Don't worry about the cylinder finish, it will get more shiny as the engine breaks in. There have been several threads in the last year about the quality of Stihl cylinders. At the end of the day, they work just fine. I wouldn't worry about it. The 46ZD11 and the word Mahle are both manufacturer markings. Stihl uses Mahle to make alot of cylinders for them, and that is a Mahle cylinder.

I plan on rebuilding the engine that is currently in the saw, maybe putting a 390 piston/cylinder on it or getting the dead one bored .120 and replated, when I get some more money. In racing you always had two of everything, except engines - I took 6 with me to a race.

Why would you rebuild the engine in the saw if you already have a complete new one? Also, boring is NOT practical on these. The cost of replating is more than the cost of an entire new cylinder. Also, the 290 cylinders have MUCH smaller transfer ports. Even if money was no object, I can't see an overbored 290 jug running very well at all due to the size of the transfers. This is also covered in the 1127 cylinder thread.

The pan does not contact the cylinder assembly, there is a gap of around 1/32". I cannot push the two parts together by hand and don't want to force something. Are they designed this way to create a "crush" on the bearings to hold them in place when the bolts are tightened down. There was no mention of this in the service manual.

Yes, you will need to bolt the halves together to get them to contact. You will need fuel proof sealant to put those halves together. Suitable substitutes can be found with a search on here, if you don't want to spring the $20 for Dirko HT from Stihl.

I plan on adjusting the carb from the factory settings to what it should be. My race engines were always set a slight bit rich, so I intend to do the same on my saw. I would also like to eliminate the "Intelli-carb" leaning out the mixture. I would just as soon have the engine go richer instead of burning down to tell me the filter needs cleaning. If there is a better carb, or some recommendation for changes to this one - I am open to that.

Intellicarb has NOTHING to do with any of your problems, and there is no reason to remove it. Intellicarb is just a port on the back side of the metering diaphragm that opens into the air filter. If the filter is allowed to get dirty enough to impede flow, the vacuum will act on the back of the metering diaphragm and lean the mixture out to compensate. There are no moving parts to the intellicarb. It is a very reliable and proven system. If you keep your air filter clean, the intellicarb does absolutely nothing. I would not remove it, and if you do, you'll need to get another air filter with the intellicarb port blocked of. Otherwise you will suck unfiltered air into the engine. I think you know how fast unfiltered air will destroy your engine.
You can find info for removing the limiter caps on your carb with a simple search. Just remove the caps, trim the tab, and push them back in.

And lastly, my plans are to dump the Stihl oil - since I have no idea of its specs and go to Klotz KL200. That is the same oil I used in my race engines that take a lot more abuse than my chainsaw. Any experience on that oil in a chainsaw would be welcome as well. I plan on running 5% (19:1) since the ethanol can be as much as 15% in the Houston area now.

Any information will be welcome.
Thanks in advance,
Fog Tanner

There are drillions of oil threads here also. 19:1 mix is ridiculous. There is no reason to go any more than about 40:1 with any modern oil. I run that in all my antiques. Some of them call for as little as 16:1, but this is for using 30w oil mixed with gas. Modern two stroke oils are much better. I run 44:1 Klotz R-50 and premium gas in everything. I have never had an oil related failure.

Good luck, and report back.

 

[benmyers]

seal replacement

Where can the thread on the substitute fuel-proof sealing material be found? I too am rebuilding a 290, and would like to read up on that!

Ben

 

[andrethegiant70]

Fog1965..... Where to start.....

You are in luck, this is the right place to come for all your answers. Most here don't like 290's. I like them because I have had good luck selling rebuilt ones. Luckily, I am stuck in CVG airport for 4.5 hours with nothing to do and free internet. I will address your post a piece at a time.



It was not the EPA that killed your 290. Unless the carb screws are all the way counterclockwise against the stops, it was your dealer's lack of setting it up right that killed it. The clamshell design of the 290 has been around for MANY years. Sadly, that is probably the way alot of OPE will go in the coming years. Maybe not as easy to rebuild, but with proper care they don't need rebuilt often at all.



Unfortunately, you may have bought parts you did not need. There is plenty to read on here about cleaning up scored cylinders. I have had better than 50/50 odds at cleaning up scored 290 cylinders. You may have gotten away with a cylinder cleanup, and a $30 meteor piston to get it back into service. Moot point now, though.



You have the latest engine iteration. From time to time, Stihl makes slight changes to the porting or other things on those cylinders. I think there are about 5 different versions of that one in the 46mm bore. They all are interchangeable. Search "1127 cylinder thread" if you care. I'll be updating that one soon with some 45mm cylinder pics. Don't worry about the cylinder finish, it will get more shiny as the engine breaks in. There have been several threads in the last year about the quality of Stihl cylinders. At the end of the day, they work just fine. I wouldn't worry about it. The 46ZD11 and the word Mahle are both manufacturer markings. Stihl uses Mahle to make alot of cylinders for them, and that is a Mahle cylinder.



Why would you rebuild the engine in the saw if you already have a complete new one? Also, boring is NOT practical on these. The cost of replating is more than the cost of an entire new cylinder. Also, the 290 cylinders have MUCH smaller transfer ports. Even if money was no object, I can't see an overbored 290 jug running very well at all due to the size of the transfers. This is also covered in the 1127 cylinder thread.



Yes, you will need to bolt the halves together to get them to contact. You will need fuel proof sealant to put those halves together. Suitable substitutes can be found with a search on here, if you don't want to spring the $20 for Dirko HT from Stihl.



Intellicarb has NOTHING to do with any of your problems, and there is no reason to remove it. Intellicarb is just a port on the back side of the metering diaphragm that opens into the air filter. If the filter is allowed to get dirty enough to impede flow, the vacuum will act on the back of the metering diaphragm and lean the mixture out to compensate. There are no moving parts to the intellicarb. It is a very reliable and proven system. If you keep your air filter clean, the intellicarb does absolutely nothing. I would not remove it, and if you do, you'll need to get another air filter with the intellicarb port blocked of. Otherwise you will suck unfiltered air into the engine. I think you know how fast unfiltered air will destroy your engine.
You can find info for removing the limiter caps on your carb with a simple search. Just remove the caps, trim the tab, and push them back in.



There are drillions of oil threads here also. 19:1 mix is ridiculous. There is no reason to go any more than about 40:1 with any modern oil. I run that in all my antiques. Some of them call for as little as 16:1, but this is for using 30w oil mixed with gas. Modern two stroke oils are much better. I run 44:1 Klotz R-50 and premium gas in everything. I have never had an oil related failure.

Good luck, and report back.

Well, that's about everything right there. Nice post.

 

[Roanoker494]

Where can the thread on the substitute fuel-proof sealing material be found? I too am rebuilding a 290, and would like to read up on that!

Ben

I am not sure where the thread is located but I do remember one was Yamabond 4 and there are a couple different sealants available from a local auto parts store. I personally get the black RTV sealant from Mopar that they use to make most all their engine gaskets.

 

[stderr]

Where can the thread on the substitute fuel-proof sealing material be found? I too am rebuilding a 290, and would like to read up on that!

Ben

Threebond 1194, hondabond, yamabond. There's a permatex version too, can't recall the name of it. Most are rebadged threebond. Find it at a dirtbike shop. If you go permatex, make sure it's the one that says it's made for regular contact with fuel.

It's not a Stihl, but this thread shows an old case being put together w. 3-bond (look towards the end of the thread): http://arboristsite.com/showthread.php?t=136292

Cheers, and good luck w. the rebuild.