Yamaha Starbike Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
Ok, I'm sorry for the lengthy post. I want to go through everything I've done and been through so it's all covered.

So I bought this bike at the beginning of the summer this year. The guy said that he bought it and hardly ever rode it so wanted the money back out of it. I rode it home which was about an hour away and had no issues with it. It has an aftermarket intake K&N filter with the little blower housing on it. It also has the oil filter relocation kit on it. It is using stock pipes.

Washed it thoroughly and polished the chrome, etc. Then went to take it on a longer ride and it started to bog down and just sounded like it was running really rough. Couldn't figure it out. Put sea foam in the tank and left for a ride and then it was like I was bogged down and the throttle would kick in and then cut out again over and over. I thought, "crap in the tank clogging up my jets in the carbs". no big deal, that I can handle.

Then my front exhaust header starts smoking a whole lot and i'm leaking oil from the header. Take the bike home to check the oil. Sure enough, it's too full. Drain the oil and refill. Then it's back to running ok again. Ride it about 20 miles and it starts by being pretty bogged down and then full throttle starts kicking in and back out again. Finally that sort of stabilizes, but it still feels a little rough. Take it to a shop and they say it's normal so I go for a 200 mile ride. No real problems other than at idle my RPMs are WAY too high. I futz with the idle screw a bit to drop that down. Fine. Still runs rough. I take the slip-ons off to make sure it's not a back-pressure issue. Same problems.

Take it back to the shop afterwards. Of course my starter clutch should happen to go out at this point so I have to buy replacement parts to replace that. got that fixed. He tunes the carbs, fixes a vacuum tube that was crushed and cleans the filter which was completely clogged. Says it's all good now. I take it for a spin and at about 50%-100% throttle I lose significant amount of power. Cuts out and back in. It's also still as rough as it was before. I give it back to him and say, no it's not fixed. Clean the carbs while i'm gone on vacation.

Come back from vacation. They say that the carbs have been cleaned (they've got a sonic cleaner thingie). They tweaked the carbs some more after getting them synced. says that it's not a significant improvement but it's better. I ride it and would agree that it's better. It's no longer losing power at 50-100% throttle. Although if I push the throttle all the way up to 100% and then back down a smidge it starts hiccuping. Guy that worked on it says he thinks that it had been sitting a while when I got it and the build-up and corrosion in the engine was working to fill all the gaps and provide better compression and now that i've ridden it a while, that has all broken down and is cleaned out so that's why it's running more roughly. He said the carbs were dirty, but not the worst he's ever seen. As a side note, they did check compression and he said it's good, but not as good as it could be.

So, my observations. I have a fairly strong gas smell when at a standstill which I see as a too rich fuel issue. I would guess that would have been fixed at the shop. These guys didn't start doing this stuff a week ago. I noticed when riding last night that the front cylinder was way hotter than the rear after getting the bike warmed up. I don't know if that's an indication of problems in the front or rear cylinder specifically, but I would think they would both be the same temp regardless. I mean, this temp was a noticeable difference. I could hold my hand on the rear and could only leave it on the front for a second or even just a tap. Now, the longer I rode, the more the rear heated up eventually, but it was not as quickly as the front.

I have also checked my fuel pump which seems to be working fine though I'm not sure how to check the flow speed while the engine is running. Maybe it's just slowing down?

I saw another post about a guy having problems with his rectifier, but I can't imagine that would be the issue.

Bottom line, I trust the shop I was taking it to, but I don't believe that the way my bike is running is the best it CAN run. I think it's got to be something simple that they're just missing. Shop guy says if I want more power I'm just going to have to bite the bullet and jump to a 1600 or higher.

I should also add that this shop mainly deals in Harleys, but they do work on other bikes as well.

Thanks for any help or direction I can get.

Adam
 

·
Registered
Joined
·
2,181 Posts
You need a new shop..... sounds like they have you totally F'd up. Take it to a real shop. These carbs are super simple, if you know what your doing. If they didn't get it right the first time, I'd have never gone back....

Even the advice on the bigger bike is totally wrong.... LOL....
 

·
Registered
Joined
·
1,090 Posts
I would agree with Mick. Find another shop. To me anytime someone tells me a problem is as good as it's going to be, that translates to "I don't know what else to do with it"
 

·
Registered
Joined
·
8 Posts
Discussion Starter #4
And trust me, that's my thought too, but I thought if anyone had any ideas of other things that I could check on my own, I can definitely try to hunt the problem down on my own first and bring in another shop if necessary. The downside to another shop is that the nearest shop that I would take it to is 60 miles away and I'd rather not have to take it that far if I can avoid it.

Thanks again for any input.

Adam
 

·
Registered
Joined
·
274 Posts
Hi Adam, I think if you can hold your hand on the rear cylinder that its likely your running on the front cylinder only. When I bought my 650 it had been sitting for a long time. The carbs were really dirty and the bike was running on only the rear cylinder. In my case the carb cleaning did the trick. It could also be electrical, can you verify you have spark tot he rear cylinder? Not sure this will help.
 

·
Registered
Joined
·
2,181 Posts
I think your main issue is in the carbs. If your confident enough to be able to figure what what the shop messed up....and make it good....I'd say go for it. They are about the simplest carbs out there to work on....but it still requires a little expertise when you are dealing with a mess like you have.

Go HERE and start reading. Just about everything you need to know is right there....
 

·
Registered
Joined
·
8 Posts
Discussion Starter #7
Hi Adam, I think if you can hold your hand on the rear cylinder that its likely your running on the front cylinder only. When I bought my 650 it had been sitting for a long time. The carbs were really dirty and the bike was running on only the rear cylinder. In my case the carb cleaning did the trick. It could also be electrical, can you verify you have spark tot he rear cylinder? Not sure this will help.
I do have spark in the rear cylinder. My thought was that with the rear cylinder temp being low plus the fact that I do have spark and there is also a fairly strong gas smell when sitting/running that maybe it's a misfire issue pointing at either electrical or timing. Of course I'm just grabbing at straws here so I could be way off too. If I can't find anything in the next day or so I'm just going to take it to a licensed Yamaha shop that I found closer.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #8
Well, the shop I had it at first was obviously incompetent. The timing gear for the rear cylinder was off exactly 180 degrees so it was in sync but exhausting my unburned fuel.

That's now fixed. I replaced the float bowl gaskets and readjusted the float levels as they were pretty high. Now I'm gonna tweak the pilot screws and double-check my balance again. I'm getting closer!

Thanks again. I guess I just needed the kick in the pants to switch shops.
 
1 - 8 of 8 Posts
Top