Six million dollar 350x No power!! Help!!

[Big Daddys 350x]

Hey guys got my 350x running again. It has a brand new top end, 12:1 weisco piston megacycle cam ported and polished head stainless valves 400ex carb with sigma 6 jet kit. Pretty sure cam part # is 162 full dg exhaust all new reweld rockers the whole 9. I run 110 in it and Brad penn oil only. Motor is almost identical to the 350x featured all over youtube. Theirs screams, mine whispers. It starts and runs but misses a little above idle turn the throttle a little more and it cleans up. Only black smoke when it's at wot and then just a little then clears out. I am so bummed. Me and my family are going to little saharah sand dunes in two weeks. I've been working on this trike since last year when we all went and I sat out cause it wasn't ready. I'm at a loss I just don't know what else to do.

The old smoking stock motor would spank the new motor. It was bone stock with dg exhaust and stock 400ex carb. Was super easy to kick start and had tons of power but smoked like a freight train. The old wore out motor would wax a 400ex with pipe and jet kit. Would even hang with my buddy's raptor.

The new motor sucks. No low end power at all, when your at wot, feels really weak. Wot from 2nd to 3rd won't bring the front tire off the ground if you tried.

It seems like the engine is dragging down when you take off up to 1/4 throttle then it stops sputtering and power starts to come on. My wife asked me why are you taking off in second gear. Feels like driving a car with the timing way retarded. This engine is pathetic really disappointed.

Guy who assembled the motor said it just needs to be jetted said he thinks it's running to rich. When I put a foam filter on the carb makes it even worse. And it ran like this with the stock 400ex stock jetting. My other motor loved the 400ex carb.

I have got an incredible amount of money in the engine. Any ideas why power is so weak. I appreciate the help and sorry to sound like a wine bag. Just don't know what I did wrong in the build. Just a side note the bike is totally restored looks like it rolled off the show room floor. I spared no expense. I would be eternally great full if someone could shed some light on my situation.

Again thanks!

[atc007]

I was thinking maybe something mechanically binding inside,,till you said black smoke. That is a very rich carb. Same set up you had before the rebuild? We've all been there bud. Tons of time ,cash and anticipation for your dream build and it flops. You'll get it figured out.

[El Camexican]

Are you certain of your cam timing and ignition timing? That needs to be confirmed first. Then get someone who knows how to jet to bring over a box of brass and spend some time with you. Have them check the float height and hose routing and then start the jetting process. That engine is too expensive for you to be learning on.

[yaegerb]

You can't just slap a hi-po motor together and expect it to run right off the bat. My best suggestion for you is to look locally for a dyno shop that allows for ATV tuning. It will cost you an extra 300 bucks but worth 6 million headaches . I can tell you right off the bat that it's rich.

[6speedthumper]

I agree with El on the ignition and cam timing. Also, make sure your valves are adjusted to the proper clearances, as per the cam manufacture's specs. You are running rich, but, you have to check the bases first, because it could be one of the above I & El listed.

Look to see if any of the vent hoses for the carb as pinched between the carb and fuel tank. I had that problem right after I put the 400ex carb on mine. Just didn't catch it at first.

Just for curiosity's sake, who's X on youtube are you talking about?

[Big Daddys 350x]

I agree with El on the ignition and cam timing. Also, make sure your valves are adjusted to the proper clearances, as per the cam manufacture's specs. You are running rich, but, you have to check the bases first, because it could be one of the above I & El listed.

Look to see if any of the vent hoses for the carb as pinched between the carb and fuel tank. I had that problem right after I put the 400ex carb on mine. Just didn't catch it at first.

Just for curiosity's sake, who's X on youtube are you talking about?

Man you guys are awesome! Just getting the comments and feedback has made me feel better. As for the 350x it's the one where they did a 250r and a 350x retro rebuild. Both seriously nice bikes.

This was/is kinda why I was a little bummed, I have worked on and built this bike for about 4 years. I have been dreaming of a 350x since they were new and I was about 12 years old.

Both of my cousins and my uncle had three of them when I was 14. The butts wouldn't even let me ride one around the yard (they would let me clean them and change the oil stuff like that) my cousin would promise to let me ride his, when it came time to ride there was always an excuse. My aunt and uncle told me I didn't know what I was doing and I couldn't handle that kind of power. So I would sit there and watch them ride and have a blast. The last time I went camping with them they promised to finally let me ride one.... I helped set up camp helped them with everything. When it came time to ride it was a big fat no. So I spent another weekend watching them ride through the river and just have a blast. The whole time I sat. I made myself 2 promises that day one was to never go camping with them again and the other was to have the most bad 350x any of them ever seen.

So at 40 years old I've finally got one and I can't wait to tell my cousin he can't ride it cause it's has way more power than his stock one did and he couldn't handle it LOL!!

So anything I can do to make it perform correctly would just be awesome!

[Big Daddys 350x]

By the way I have a goki starter on it too, and with the decompression cable working that starter will bust a 12:1 motor right off (with a little battery don't have my new one yet) I also put a 400ex starter switch on it. This has been a long project. When I bought it, what there was of it it was all in boxes. It was a motor and a frame with broken front forks and a box of bolts. Boy was I a moron... That's why it's the six million dollar 3 wheeler.

I will try all of your suggestions and let you know what I come up with! Again thank you.

[jays375]

With that cam stock specs won't work on valve adjustment.Better check that quick.Same carb and jetting as before?Do a quick compression check.The guy who assembled it has experience?Did he do the head work?

[El Camexican]

With that cam stock specs won't work on valve adjustment.

Are you saying that the lash setting will be different that stock with a different cam? Please explain.

[jays375]

Stock specs are to tight.Which you should see hard starting if tight.Still should be checked.Heavy duty valve springs installed?

[DohcBikes]

I swear I'm not picking on you yaeger, but I do disagree with everything you posted.

You can't just slap a hi-po motor together and expect it to run right off the bat.

B.S.!!!!!!!!!!!!! People get paid lots of money to deliver an engine that runs right. Tuning should be included when you bet the farm on a one cylinder engine. This is not rocket science kids.

My best suggestion for you is to look locally for a dyno shop that allows for ATV tuning. It will cost you an extra 300 bucks but worth 6 million headaches

Holy hell back up here. Pay another shop to tune the one cylinder motor another shop built? Please don't do this.

I can tell you right off the bat that it's rich.

No you can't!!

First of all, take it to the person you paid to build it. Tell them you are disappointed. If all else fails, pm me. I'll build you an engine that runs perfect the first time you ride, GUARANTEED.

[Big Daddys 350x]

Stock specs are to tight.Which you should see hard starting if tight.Still should be checked.Heavy duty valve springs installed?

Yes the valves were set per megacycle's specs. When I purchased the cam from megacycle I bought all the matching componets they told me I would need to use their cam.

My buddy is the one who built the motor, another guy built it for me and shipped it to me said it was all new. When we mounted it in the frame it would not kick over. My buddy tore down the entire engine to find a flat head screw in the motor. When he pulled it apart we found out that it didn't have any of the parts in it the original builder said it did. And the parts were used. So we took the two 350x motors I have and built one good one. I paid $750 for the first motor with a screw in it and used wore out parts. Then my buddy cometely reassembled the entire case/Trans the whole motor, that's when we installed everything from cylinder up brand new, except the head. It came was from the second motor and had come frome a atv race shop in Nevada where they did the pro port work and valves. You could tell all that was brand new and that it was a prof port job. All clean and smooth no gouge marks or grinder marks. In my buddy's defense he has a big family and not much time that's why I'm comming to you all here to try to take out as much guess work as possible. Sorry guys I know I keep writing books here I'll try to keep my comments shorter. Just trying to give as much info as possible.

[DohcBikes]

Yes the valves were set per megacycle's specs. When I purchased the cam from megacycle I bought all the matching componets they told me I would need to use their cam.

My buddy is the one who built the motor, another guy built it for me and shipped it to me said it was all new. When we mounted it in the frame it would not kick over. My buddy tore down the entire engine to find a flat head screw in the motor. When he pulled it apart we found out that it didn't have any of the parts in it the original builder said it did. And the parts were used. So we took the two 350x motors I have and built one good one. I paid $750 for the first motor with a screw in it and used wore out parts.

And you expect it to run great?!!! So much wrong here.

You have "an incredible amount of money" into the engine you just described. Tough nuts man.

[Big Daddys 350x]

I swear I'm not picking on you yaeger, but I do disagree with everything you posted.

B.S.!!!!!!!!!!!!! People get paid lots of money to deliver an engine that runs right. Tuning should be included when you bet the farm on a one cylinder engine. This is not rocket science kids.

Holy hell back up here. Pay another shop to tune the one cylinder motor another shop built? Please don't do this.
No you can't!!

First of all, take it to the person you paid to build it. Tell them you are disappointed. If all else fails, pm me. I'll build you an engine that runs perfect the first time you ride, GUARANTEED.

The first guy is the one that screwed me I paid and ton of money for a motor that was supposed to be a bolt on and go. I got ed because it was over the internet deal. I got nothing for a refund all I got for my 750 was a pretty nice head and bottom end. Witch really I can't complain I know what those parts cost and I understand the value. My friend is a ase certified auto tech. And has built many atv motors, he was being a pal and helping me out. I don't want to throw him under the bus cause if it wasn't for him I wouldn't have gotten it to this point. With 4 kids he doesn't have much time. So I am trying to figure this out kinda on my own.

I honestly and sincerely appreciate your time, and help. If we can't get it figured out I would be happy to pay for any further work done.

[DohcBikes]

This motor you have is going to be a bear to diagnose, but it runs. try stuff. Check the timing, check the valves, again, change the jets, check the float height, fuel, air delivery

oh wait!!!!!.

Check the compression.

Do a leakdown test.

Hire a mortorcycle mechanic.