|
|
Post by jselden78 on Jun 30, 2019 17:15:57 GMT -5
Good evening fellas. I have a question about rebuilding a tillotson carb for a super XL 925. Its been quite some time ago but I acquired three 925s to go with the one I already had. I have got three total running now but I am having trouble with one in particular. I think I had asked this before but I got side tracked and actually mixed a few carbs up and for got which one was the problem. I have gotten past all my fuel line issues (big shout out to Leon for that) and I have two running great now. The third one I have learned is that carb with the problem. Its hard to get it to pick up from low idle to wide open but once it does man it is screaming. I didn't put my tach on it yet but I'm gonna say its somewhere north of 15 or 16k rpms. I was told when I got the saws that one of the carbs had been modified and the check valve "punched" out and replaced with one from a Husqvarna or something to that effect I'm quite certain at this point for some serious performance increase. I on the other hand am not interested in that and would like it to last a long time as opposed to flying apart. My question is what would've been changed and can I change it back or would I be better off finding another carb and putting this one in the scrap pile?
|
|
|
|
Post by undee70ss on Jun 30, 2019 17:41:38 GMT -5
Welcome back!!!! Tillotsons on SXL925's are a fixed jet with high speed trim, and tuning one is a little different than a normal carb. Also it sounds like someone plugged the governor valve, with prevents the saw from over speeding
|
|
|
|
Post by undee70ss on Jun 30, 2019 17:43:55 GMT -5
|
|
|
|
Post by jselden78 on Jun 30, 2019 17:46:08 GMT -5
Yea I have adjusted a few successfully already and the high speed is almost closed maybe 1/8th turn out. This one though, I can open it two and three turns and it still runs way too fast. When I say screaming it is absolutely screaming. I'm going to try and check it with my tach but its an easy 16,000 rpms likely higher. If it was modified, which he said it was, is it possible to replace something and have it back as it should be? I just don't know what would've been replaced or "punched" out to make it run this way.
|
|
|
|
Post by undee70ss on Jun 30, 2019 17:51:43 GMT -5
When someone modded the carb, no telling whats been done, but for sure it sounds like its running to lean. Try a carb from one of the other saws.
|
|
|
|
Post by jselden78 on Jun 30, 2019 18:00:31 GMT -5
When someone modded the carb, no telling whats been done, but for sure it sounds like its running to lean. Try a carb from one of the other saws. yea I really hadn't thought of that I think I will next chance I get. In the mean time I might just see if I can run down another carb for it. Is the tillotson the only one for that saw or was there a walbro as well? I think there was an HDC made for it wasn't it? |
|
|
|
Post by undee70ss on Jun 30, 2019 18:20:41 GMT -5
When someone modded the carb, no telling whats been done, but for sure it sounds like its running to lean. Try a carb from one of the other saws. yea I really hadn't thought of that I think I will next chance I get. In the mean time I might just see if I can run down another carb for it. Is the tillotson the only one for that saw or was there a walbro as well? I think there was an HDC made for it wasn't it? No HDC. The late model SXL925’s came with a Walbro WJ27. |
|
|
|
Post by jselden78 on Jun 30, 2019 18:52:23 GMT -5
yea I really hadn't thought of that I think I will next chance I get. In the mean time I might just see if I can run down another carb for it. Is the tillotson the only one for that saw or was there a walbro as well? I think there was an HDC made for it wasn't it? No HDC. The late model SXL925’s came with a Walbro WJ27. was it a fixed hi speed as well like the tillotson? |
|
|
|
Post by 5terrysupersaws on Jun 30, 2019 19:26:42 GMT -5
Yea I have adjusted a few successfully already and the high speed is almost closed maybe 1/8th turn out. This one though, I can open it two and three turns and it still runs way too fast. When I say screaming it is absolutely screaming. I'm going to try and check it with my tach but its an easy 16,000 rpms likely higher. If it was modified, which he said it was, is it possible to replace something and have it back as it should be? I just don't know what would've been replaced or "punched" out to make it run this way. Inspect the Governor Check Valve(brass plug on r/h of carb.) for modifications, sometimes plugged with a metal disk and re-installed.. or maybe "punched" out. New valve #70334 available on eBay. New carburetor available at Leon's. Glad to see you back! Good luck with it! |
|
|
|
Post by undee70ss on Jun 30, 2019 22:57:43 GMT -5
No HDC. The late model SXL925’s came with a Walbro WJ27. was it a fixed hi speed as well like the tillotson? Yes |
|
|
|
Post by sweepleader on Jul 1, 2019 19:01:23 GMT -5
Welcome back!
I had a 925 that was way too rich and I plugged the governor valve. It was a small ball that rattled out of checking position with too high of a speed. It allowed extra fuel in to richen things up and slow them down. I put in a solid disk to prevent the excess fuel thus allowing the needle to adjust the high speed. Worked fine.
Sounds like that might have been done to yours but it went too far.
I would be inclined to try for another carb that had not been messed with, rather than try to figure out what someone else did to it.
Of course if you want a race saw, you are all set up.
|
|
|
|
Post by onlyhomelites on Jul 2, 2019 0:21:07 GMT -5
It may be all in terminology, but about all that might be "punched out" would be a main nozzle. If this has been changed with one that is too small, no amount of tuning will fix it. If this has been changed, you can change it back with one of these from Ebay. None of these guys knows what they have for sale...it's a check valve not "choke valve": www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=homelite+69793&_sacat=0&LH_TitleDesc=0&_fsrp=1&LH_PrefLoc=3&_sop=15&_osacat=0&_odkw=homelite+03599&LH_TitleDesc=0&_stpos=97535The governor valve is also prone to trouble, but the last few I have been able to "fix" with a quick application of brake cleaner and then compressed air through one of the orifice's. I also lightly move the check ball off the seat a couple times to make sure it isn't stuck. I've done this on a 925, 922 and 910 all in the past month with good results. With the hesitation you are describing though between low and high speed, that sounds like a possible starvation issue...really seeming to point to the nozzle if all else is good I like sweepleader's idea of trying a known good carb...this will eliminate crank seals and other non-carb potential issues. Great to have you back John! |
|
|
|
Post by jselden78 on Jul 4, 2019 16:34:39 GMT -5
Inspect the Governor Check Valve(brass plug on r/h of carb.) for modifications, sometimes plugged with a metal disk and re-installed.. or maybe "punched" out. New valve #70334 available on eBay. New carburetor available at Leon's. Glad to see you back! Good luck with it! I believe you are on to it here. I had a few minutes today and pulled the carb. I turned it up to remove or attempt to remove the governor check valve and immediately so that it was not sealed with the same sealant I have seen used on most other carbs I have dealt with. I have never removed one before, I tried once but the red sealant around it certainly had it in there. I was able to remove this one with little to no effort and the sealant that was used to put it back in was still not really dry. I can't tell if its been modified because I really don't know what it should look like. I'm going to just try and replace it and the check valve put a new kit in and see what happens. I will try and get pics later and upload but I've got a 4th of July event to attend this evening for the new company I started working for about 3 weeks ago. Thanks for all the input. |
|
|
|
Post by jselden78 on Jul 6, 2019 15:43:11 GMT -5
Well I am glad I waited before I ordered the governor and check valve for this carb. I decided to wait until I posted some pics and once I did I think I found something. I am attempting to attach and album from flickr here but it has been some time since I used flickr and it has changed a bit. Anyway in one of the picture of the carb where the governor was removed it looks as if it is two holes inside, one bigger than the other. I am think that two was maybe not factory? I don't know as I've never seen the inside of this port on a carb so I figured it best to let some experts review this first. if the pics don't show up give me a few minutes or so I will try to work that out. flic.kr/s/aHsmERG7S5 |
|
|
|
Post by jselden78 on Jul 7, 2019 18:52:19 GMT -5
I thought I had another 925 carb around so I set out to find it tonight and surprisingly I did. I had a kit on hand too so I went ahead and put a kit in it. I then checked the governor check valve and it too was not as tight as I remembered some others being that I attempted to remove but it was tighter than the one in the carb that started this thread. I removed the governor and it look the same as the other one. I then looked in the carb port and this one only has one hole and it isn't as big as the biggest hole in the one in my picture above. Also it doesn't have the copper washer that you can see in the other one. I don't see that washer on the IPL so I assume its not needed. I put this one back together with new kit and it did change the way the saw ran a bit. I starts okay but wouldn't take much throttle. It also wouldn't idle very well, acted as though it was getting air or leaning out. I went ahead and pressure checked the lines from the filter out and the carb and found no leaks so now its on to the crankcase check. Does anybody know what kind of sealant Homelite used on those governor valves? it looks like Loctite 262 but I wouldn't think that's what they used but I could be wrong.
|
|
|
|
Post by jselden78 on Jul 7, 2019 18:55:53 GMT -5
Allow me to correct myself, I do see that copper washer under the governor valve on the IPL. That might be some of my problem there with the different carb. I might take the one out of the carb with the hole knocked out in the port and put it in this one and see how it goes.
|
|
|
|
Post by jselden78 on Jul 13, 2019 16:25:49 GMT -5
So I'm not really sure what the purpose of that little copper washer is under the hi speed valve but I put it in the carb that was missing it and now it looks like I have another good running 925 which makes 3. I did say good running though. It needs a little bit more fine tuning but I immediately noticed that the automatic bar oiler does not seem to be working. The manual oiler worked but the auto did not seem to. It has a practically NOS 24" homelite bar on it so I stopped immediately. Once I get that corrected I will finish the carb. Now...if I can find a good p and c for a 925 I might have 4 running lol.
|
|
|
|
Post by 5terrysupersaws on Jul 13, 2019 17:11:07 GMT -5
So I'm not really sure what the purpose of that little copper washer is under the hi speed valve but I put it in the carb that was missing it and now it looks like I have another good running 925 which makes 3. I did say good running though. It needs a little bit more fine tuning but I immediately noticed that the automatic bar oiler does not seem to be working. The manual oiler worked but the auto did not seem to. It has a practically NOS 24" homelite bar on it so I stopped immediately. Once I get that corrected I will finish the carb. Now...if I can find a good p and c for a 925 I might have 4 running lol. The copper washer under the governor valve may be there to prevent fuel and possibly air from by-passing the valve, as the orifice under it leads to the venturi. " Governor valve resonates at a desired engine speed and directs excess fuel into the carburetor bore to prevent over-speeding. " NOS cylinder (82cc version) available at our favorite store. |
|
|
|
Post by jselden78 on Jul 13, 2019 17:32:47 GMT -5
" 5terrysupersaws"The copper washer under the governor valve may be there to prevent fuel and possibly air from by-passing the valve, as the orifice under it leads to the venturi. " Governor valve resonates at a desired engine speed and directs excess fuel into the carburetor bore to prevent over-speeding. " NOS cylinder (82cc version) available at our favorite store.[/quote] Yea I spotted that the other day but I am compiling a list of should I say cheaper parts right now for a couple of other saws on the bench. I think three of those 925 is enough for me right now lol. |
|
