jaykup

Sounds good, I saw a refrence to this tool in my manual. Yes, I did clean out the air jets. I think you may be right on that too, because it only likes to fire on FULL CHOKE. I wil check the local yamaha dealership, and see if they will order me one, its worth a try. If they can, ill have em get two, if you need one Ill see how much they are first of course. But, this being sunday, I am sure they are closed. Ill let you know soon Yes, it is a yics, my friend with his interceptor is always like.. YICS, constantly saying it when ever he sees my bike.. : Haha, anyway, ill let you know. Jake

I've got this Seca 750 and had it running after i bought it. I didnt do anything to it at that time, and it seemed to run OK except for low-end throttle, it seemed as though it was miss firing. As soon as i would give it gas, it would go just fine. I figured it was carb related, from sitting forever, and I was right, the carbs were extremely dirty. One of the smaller jets was clogged, and I am guessing that is what made up that low end missfire. I cleaned out all the jets, everything. Carb cleaner, air-compresser, the works. The floats were still in adjustment (17.5MM) as I measured them all The floats are also in good shape (did the hot water test to find leaks, nothing). I cant brake free the bottem drainage screws, but everything else was taken apart. (except the mixture screws) Now the bike wont start. The two far cylinders (1 and 4) are firing, but the middle arnt. All are getting spark, new plugs just installed. The spark to me seems weak, but its there. the main thing is, the plugs arnt wet when im turning it over and over and over. So i thought i messed something up in the carbs. I took them off, and all the bowls had alot of gas in them. Same amount from what I could tell. I know the jets are cleaned, just double checked them today. For a while, I had it idling, and i could rev it to around 4K or so just fine, even higher, but as soon as I tried to take off, it just died. Like it was running out of gas. Which is why i went to the floats, and the needles. What would be causing this? What else did I miss? The thing ran great before i tore the carbs apart, so i really dont think its spark The coils tested 20K and 30K or so, and they were supposed to be around 25K. Also all are sparking. Where do I start? The petcock also flows great. Jake

haha no way!!! I've got a 1981 Seca 750 I got from some guy who had to sell desperately for some reason. The seca is a powerhouse, I'll give it that. But the little 350, if it were running right, I think wouldn't do too bad against it. With some better pipes, intake, and what not, I think it would be dead even with the seca. The seca didnt seem to handle all that bad, the R5 was definitely better. The guy before me put straight pipes on the damn thing too, and with the way it vibrates, it sounds like a mean rocket after 6K. It needs a new starter too. I've got some pics of it, I only got this one for 250, so its not in too good of shape, I was thinking of restoring it over the winter as well. Both fun bikes Your's looks ALOT nicer, I like the rims as well. Nice work with that! I've also got a 1979 Yamaha XS 750 : The damn second gear is F'ed just like all the other ones. So right now its just kinda sitting. Its a fun bike though, 5th gear accel is pretty nice.

I figured someone would notice http://digitallywarped.mine.nu/bikes/Yamah...0350%20dust.JPG http://digitallywarped.mine.nu/bikes/Yamah...350%20dust2.JPG http://digitallywarped.mine.nu/bikes/Yamah...350%20clean.JPG http://digitallywarped.mine.nu/bikes/Yamah...50%20clean2.JPG as you can tell from the first pictures it was pretty dirty when i got it. i didnt fully go over it and clean it, but I did spray it down and it got most of the dust off I got it for 100 dollars, and its been a handful trying to get it to run right. Right now for some reason.. when i get done riding, only sometimes, it poors gas out of the overflow. I checked the float slides and they move very smoothly, and the float I think is set right. I just now bent it up so the gas would shut off faster, but now it wont start at all ... damnit. I'm going to have to find the float setting and do it right. It sure is fun when it runs though, Raced my friends 1982 Kawasaki KZ650 CSR and beat him up to 90MPH Pretty impressive out of a little 350 Anyway, theres the pics, thanks for the help too.

Yeah, I really want to get the electronic Ign. Soon I hope. Actually, dont yell, but just to get it to run i put a different battery in it, slightly larger, and the airbox had to be moved forward a little, and i didnt have room for hte intake boots, so its just an open carb. I know, but I need to get the Y-pipe filter ive seen for these, seems to be the best fit. I messed with the points a little, and got it to run a bit better, in the higher gears it still seems to lose power. Im guessing its the timing now.. and maybe there was too much air with open carbs like that. Whats a good way to get the bike timmed correctly? Also, could the baffles be clogged a little? One cylinder seems to fire more powerful than the other (according to the exhaust) just seems to have more of a UMPH to it. I'm thinking too the points should just be replaced (how much are they?) if there expensive, ill just go with electronic right away. How exactaly do you clean out the baffles? Thanks again for the replies

I checked the plugs, only to find that one of them was the wrong one, and the other was correct. Not only that both of them were pretty fouled out. I replaced the plugs with NGK BR8HS. THe guy at the yamaha dealership told me that they were the same plugs that I looked up on them "B8HS" except they were resister plugs... to me that sounds like its going to get a weaker spark. Whats the difference? Also, How can I make this thing run leaner? I drove it about a mile, and the brand new plugs are pretty black already. I'm not sure if all two strokes run this dirty, but to me it just seems rich. I cleaned out the points once, then drove it about 100 miles, cleaned them out again (no spots on them) and it seems to be pretty smooth, until I hit about 7K at full throttle, it seems to want to bog down. Shouldn't these bikes scream up to redline? First gear still pulls up the front end a little bit when the powerband hits, but not very high at all. Few inches off the ground. I have both carbs completely cleaned out, twice.. and I set the larger screw to 2 and a half turns out, and the smaller screw to 1 and a half turns out. It wont idle like this.. unless I turn the large one in about a full turn or more, but then I'm thinking thats going to make it run richer than normal right? I still need to understand alot about these two strokes, and adjusting/tuning them. As soon as i get some more money, I was going to just go with electronic Ignition so I dont have to worry about these useless points. I'm out of ideas, and I dont think its running right, anyone have any comments?