Racinbob 11,544 #1 Posted December 21, 2013 I tried to post this on a Tecumseh forum but it won't let me post a picture. I'm hoping somebody here can help. I have a Coleman generator with a Tecumseh HM-100 fixed speed motor. It was surging badly so I pulled the carb (#640260) and completely rebuild it. Before I removed the float I noticed that the level seemed way off. Instead of 11/64ths it was probably 3/64ths. In other words, the bowl fuel level would be very high. It also seemed odd to me that there was no needle valve seat. it was a metal to metal seal. Everything I found online showed a rubber seat and the kit I bought had one. A bit confused I went ahead and put the seat in (making sure it was fully seated) but now the needle valve pins the float in the fully down position and there is no way to adjust it that much. Do some of these NOT have a rubber seat? Next, stupid me decided to mess with the governor adjustment. That was before I pulled the carb. I shouldn't have touched it cuz I'm sure it was fine. Is there a starting point to set it before I fire it up again? I search the world over and couldn't find a governor set up like this. The only thing I messed with is the nut you see near the rod. I just need a good starting point then I can fine tune it to get the hertz at 60 and hold that under load. Share this post Link to post Share on other sites
Racinbob 11,544 #2 Posted December 21, 2013 I think I'm gaining ground. I downloaded the Tecumseh L-head Engine Manual. That nut on the governor is the high speed RPM adjustment for constant speed applications. That simplifies things a lot.Get it running again and just set the RPM so I have a 60hz output. That pesky needle valve seat still has me puzzled. For my exact card they show a rubber seat. Share this post Link to post Share on other sites
Coadster32 793 #3 Posted December 22, 2013 Shooting from the hip....Some seats have a rubber o-ring, and a metal needle. Some have metal seats, and a needle with a rubber tip. Haven't seen one metal to metal, and doubt it would work that way. I agree with your putting in the rubber o-ring. But if the adjustment is really that far out of whack, it still might not be seated in all the way. I do know there's a "special tool" to seat them in. Typically I set the float parallel to the bowl flange. (carter carbs as well). Never have I actually measured the gap, and haven't had any problems. Hope this helps. Share this post Link to post Share on other sites
rydogg 186 #4 Posted December 22, 2013 (edited) These have a little rubber O ring that sits inside the seat it is hard to see but it is there.....a little pick will remove it and you will need to put the new one in the correct way they do have an up and downside. I am pretty sure I have tecky carb kits here I will get a picture and post it. Edited December 22, 2013 by rydogg Share this post Link to post Share on other sites
shorts 182 #5 Posted December 22, 2013 Metal to metal needle and seats were the standard on most of the old flathead engines before fuel resistant synthetic rubber compounds were developed, clean fuel and the vibration of the engine seemed to keep them working properly, also they were usually gravity fuel systems without fuel pumps Share this post Link to post Share on other sites
Racinbob 11,544 #6 Posted December 22, 2013 Well, I got the float figured out. The carb is now sterile and the adjustments are set correctly. Still surging. I'll play with the governor more tomorrow. I'm about to toss in the towel. I'm not dumping any more money in this thing. If I can't get to run steady I'll be getting a pto driven generator for my Wheel Horse. I had a 5kw up north. If I can find another one it would be great otherwise it's not a difficult project to build one similar to the Wheel Horse style. Actually, building one would be even better. I would like to get a little larger one. Share this post Link to post Share on other sites
Coadster32 793 #7 Posted December 22, 2013 Metal to metal needle and seats were the standard on most of the old flathead engines before fuel resistant synthetic rubber compounds were developed, clean fuel and the vibration of the engine seemed to keep them working properly, also they were usually gravity fuel systems without fuel pumps Didn't know that. Share this post Link to post Share on other sites
rydogg 186 #8 Posted December 22, 2013 Guess I haven't noticed any metal on metal needle and seat combinations I would think these would leak due to a poor seal especially when the engine is not running. On the newer teckys like the HM-100 they used a needle and rubber seat as I pictured here. Share this post Link to post Share on other sites
rick 239 #9 Posted December 24, 2013 Are you sure the passages in the bowl retaining screw/jet are clear? Share this post Link to post Share on other sites
flyovrcntry 115 #10 Posted December 24, 2013 Surging is not normally caused by a dirty carb or needle valve issue.I have found surging is usually a carb or gov linkage problem.The linkage willhave play or slack in it causing the throttle to fluxuate.Also check the throttle shaft to make sure it fits tight,with no wiggle.Also a carb sucking air around the carb,intake gasket will do it. Yeah,trying to adjust the gov is a bad idea.You should never try to adjust it unless you had to replace a part on it or it was damaged in some way.Just do a search on adjusting the gov for that engine,or post in the engine section and and Im sure someone on here knows how to set it. Share this post Link to post Share on other sites
