Stuck in high rpm

Ok shims done and in spec. What a bit of a pain. Ignition coils tested spec. Caps tested spec. Carb bench sync with buissiness card. Spark is present. Fuel is present. BUT SHE WON'T START!!!! Where did I go wrong? It started before I messed with ignition coils. Maybe I missed something on reassmble.

 

I just tried again, Checked spark on all 4. It's there. I can smell fuel from exhaust. It grumbled for one hot sec this time around. According to the manual if spark is present across the board ignition system can be considered good. So I have spark. fuel. air. but no running motorcycle.

 

IF, ...

You got Spark ...
You got Fuel ... and,
You got Air ...

You need Compression.
What you got for Compression Numbers?

 

plugs changed or cleaned very recently? It is very easy to foul them during diagnosis...
All your safety switches checked, in neutral, clutch in, etc

Cheers
Dave

 

I see this topic went in a totally different direction, but thought I should post my recent experience. Especially since the first post of this thread sounded very similar to my problem.
After having my Maxim 750 sitting in storage for the last three years, I decided to get it out, rebuild the carbs and see if I could get it running. It runs beautiful, but would occasionally start to run at a higher RPM and get stuck for a short time in the 3-4K area and sometimes slightly increase RPM. It also did this years ago and was pretty frustrating since it wouldn't always do it. Well recently we had a really hot day and it got a lot worse and I finally found the problem. It was the throttle cable! The throttle cable was getting slightly pinched between the gas tank and frame and not releasing the carbs to their idle position. I rerouted the cable and the problem is totally gone now.

 

Have you checked the battery recently? Just because you have spark doesn't mean it's enough....

 

Haven't checked compression. Plugs I will swap out and try again. safety switches so far all seem fine. Throttle cable fully functional no hang ups. Battery full of juice with great charge. I have the pilot screws out 2 1/2 turns. Thought maybe fuel too rich to start. Also am thinking fouled plugs. Possible wrong gap as well. Going to try plugs first.

 

Ok today changed plugs and she fired up. Got a good idle and shut it down. Hooked up manometer to start working on vacuum and started it up. Kicked into high rpm around 3.5k. Turned off and restarted. Same result. Did it again started stalled. Open choke started. rpm started rising fast and lowered choke then stalled. What am I doing wrong?

 

Did you leave any of the vacuum caps open when you hooked up your manometer? Could be an air leak there.

How far off was the synch? if it was way off then that can cause your issues.

 

The carb was just rebuilt. So I'm sure it's off. The manometer is a homemade one. If I missed a spot it would just pull the fluid into the engine quickly.

 

Hurrying.

Did you block YICS before hooking up the manometer?

Also, be aware: While the motor is in the process of warming up, it takes VERY LITTLE movement on the choke lever to go from revving too fast to not running at all. Just little "nudges" toward off as it warms up.

How are the float levels; how did you set them?

 

floats set with clear tubing method. Dead on. NoI didn't block YICS. That could be it couldn't it. I have noticed the little nudges method for the choke. So not blocking YICS would cause this problem?

 

it can. And it also doesn't allow you to do the synch properly per the manual.

 

Blocked the yics and no start. Maybe I need new plugs. Maybe I fouled the old ones.

 

Ok homemade yics in. homemade vac gauge hooked up. won't run without choke . Did i miss something? Valves in spec. floats dead on with clear tube. colortune on order. new plugs and caps. gap .028. warmed up engine prior to vac gauge and yics. don't understand where I'm going wrong.

 

What are your idle mix screws set at?

If it dies without the choke it's likely not getting enough fuel to run and you'll need to open the mix screws a bit. Try a half turn first. They may go back in or out farther as you tune.

 

Does your homemade tool sufficiently seal the passage to the outside? It has to seal tightly against the cylinder block at the hole, or the YICS port on whichever side you're going in from will be open to the outside. The outer YICS passages are very close to the outside; a lot of DIY YICS tools fail to address this vital point.

 

How would I know if the YICS doesn't seal?
http://home.westman.wave.ca/~jbe/YICS.htm
that is the link to the one I made. I was very carefull to get the measurements correct. Mix screws at 2 1/2 turns.

 

I put the bike in the shop today. I can't take the stress of this and have to let an expert at it.

 

You found a shop to work on it? and how "expert" are they?

I hope it comes out well for you. Nothing worse than paying someone to fix your stuff and it comes out the same or worse than when it went in.

 

I hope it comes out well too.

 

That one has no provision for a seal between the washer on the "outside" end and the side of the cylinder block where the tool is being inserted; as illustrated it will not work correctly. It would leave the outside YICS passage effectively open to the outside.

Yeah no kidding. Does this shop even know what a YICS block-off tool IS??? Do they have one? Did you see it? Or are they going to make an incorrect one from plans they find on the innanet? Or better yet, tell you it wasn't needed?

Ask OldBikerDude how much he paid the shop that screwed his bike up and forced him to learn to do it himself. Hopefully your experience is better, but the fact of the matter is, this particular strain of old bike is beyond most shops' capabilities anymore.

 

I just keep thinking there is somrthing stupid I missed on that bike keeping me from getting it going. My wife is paying to get it fixed for me for fathers day because she is sick seeing me go through hell with it. I am keeping in mind it may not be tuned to spec but I have an understanding of how to tune it right when I get it back.

 

I just want to thank everyone for all the tremendous amount of help I got here. Big shout outs go to Bigfitz52 for "keeping it real" and slapping me upside the head when I wasn't listening, and for all the hardcore true specs I so needed, JeffK for the shims YOUR A LIFESAVER!!! Oldbikerdude and Rick for your generous offer to help over the phone , and thanks go out to everyone else I missed. You guys taught me alot and I'm sorry I gave up and gave it to a shop. I hope I will never have to put it in the shop again. I just know I missed something small and stupid. Thank You Everyone!!!!!

 

Ok stopped up at the shop. They found no spark. So it seems the spark is working sometimes and sometimes not working. So I guess that was what I was missing.

 

Classy move with the shout-outs and Jason, there is no doubt that everyone here wants your bike to run well, safe and reliably for years and years. There's no question that it was "something small"...it nearly always is. We're all hoping against the odds that you get treated fairly by the dealer and I for one, can appreciate how much your wife loves you to invest her hard-earned money into paying to get your bike fixed.

If I got my wish for you it would be that you had it back fast enough to have a VERY happy Fathers Day!

jeff

 

Thanx Jeff. This shop is family owned. They like to keep it as cheap as they can. They charge $40 an hour and they stop at $40 and tell you whats wrong and how much to fix. They are well liked in the biker community and by biker friends of mine for their quality and price. I hope I'm riding sunday for a very awesome fathers dayLOL

 

Do they understand about the various safety interlocks like the sidestand switch and cutoff relays? You might want to let them in on the "secret" so they aren't being schooled on your money.

 

Ok been researching this spark issue. Found it may be the tci. So I went to the shop and pulled the tci. Had real bad corrosion on one of the 2 plugs. Sprayed contact cleaner and hooked back up. Bike fired right up. So I took the tci home. Cleaned all contacts with sandpaper. Tested all points with meter and she checks out perfect. So off to drop it off tomorrow and hopefully get this bike back soon.

 

Bike is back and running!!!! Sounds better than ever. Cost $106.25 for pickup and carb sync. Had butterfly valves way off and idle too high. Also TCI connections were covered in crud. I'm so happy to have it back.

 

Just keep an eye on the plugs. XJs LOVE to run too lean--- right until they blow up.

 

Oh I'm going to colour tune her as well. Yeah I've read about too many people running lean and killing a bike. Thank you for the tip. I'm so glad to have it back. About to go ride now!