1985 Maxim X hard to start

Fuel - check
Spark - check
Start - epic fail

I've cleaned the carbs and checked and rechecked the float levels, I used the clear tube method and they are spot on. I also tried starting fluid and it didn't help.

It has good spark, and the plugs are new and correctly gapped.

Put a brand new fully charged battery on it, and if I try long enough it will finally start but it won't rev up even at WOT for at least a few minutes, it stays at about 1100 RPM. Enrichment circuit makes no difference during this time but once it warms up a bit it acts normally and will quickly rev to redline and drive normally, and I can kill it and restart it very easily.

Let it set over night though, and I am back to square one. Ambient temp here has been between 50F and 60F, so it's not cold at all.

Does anyone have any ideas about what I can check next?

Thanks in advance

Jim

 

Sounds like your enrichment circuit is plugged up. There's a link to cleaning it somewheres. Especially since you say that toggling the enrichment circuit "makes no difference". It's probably not working at all.

Also, you may need to sync your carbs and adjust the idle mixture screws. Once you finally get the bike running, put some miles on it and check the plugs. See if they're brilliant white. You might also be running lean which would compound this problem.

 

I think I didn't make myself very clear, writing is not my strong point. (I'm not sure I even have a strong point) so let me try it again.

After the engine warms up, the enrichment circuit functions as it should. In fact, every facet of the bike works prefectly. And as long as I don't let it sit for more than a couple of hours it will restart and run perfectly.

I'm almost certain that it is not a starting problem with the carbs, since spraying starting fluid into the airbox doesn't even make it burp and once I finally do get it started it runs great. great acceleration, smooth idle, good engine braking (did the clunk test on the slides and polished them and their bores).

Jim

 

Vacuum leaks maybe?? You can use an unlighted propane torch to check for leaks. Increse in RPM indicates the propane being burned, thus vacuum leak.
P.S/ Don't leave the propane on for extended periods, for obvious reasons

 

Jim, I have had a similar problem. Thing is a beast to start when she is cold. I found that carb cleaner is easier to get the bike to start with. The only thing I could say is maybe weak coils or somehow somewhere you aren't getting fuel.

One thing that stuck out in your post was you have new plugs. I'd double check the fuel mixture screws. My bike was horrible to start after I redid her and on a hunch (ok, on this site) I pulled the plugs...white as can be. I was lean, even though I was at 2.25 turns out. I'm over three turns out now and she starts and runs soo much better. How is your compression?
what about valve clearances?

 

I'll go and try that right now with the unlit torch.

Would a vacuum leak only affect the engine when it is cold, since it starts so easily when the engne is warm? Maybe somthing is getting warm and expanding so as to seal a leak?

P.S. I put new boots (airbox to carbs) on it, but I didn't replace the intake boots (carbs to head) since I didn't "see" any cracks. Those are going to be a pain if they are leaking.

I'll let you know if I find any leaks, thanks!

 

You engage the fuel enrichment circuit when the engine is warm? What are the results? The f/e circuit is only supposed to be necesary when the engine is cold.

The propane and idle screws are worth checking out as previously suggested.

 

I tried the unlit torch test and I did not notice any change in RPM's.

I don't normally engage the enrichment circuit when the engine is warm because it is not needed, but if I do it makes the engine rev up as it should.

I only mentioned it in my first post because it has no effect at all when the engine first starts after getting cold. It makes no difference if I have it on or off when the engine is cold, but it does seem to work correctly after the engine is warm.

I just bought a compression tester, but I have never used one before. Any pointers? Does the engine need to be cold to do a compression test?

I'll give the mixture screws a turn out, but I will have to wait until the engine is cold again to see if it helps, because it starts so very easily when the engine is warm.

Thanks people, any more ideas?

 

Is there a walk-through for checking the valve clearances?

 

Make sure the throttle is wide open when checking the compression.
Definately check the valve clearances...and yes it is a PIA on the X

I'd second mcrwt644 with you being too lean.
Once it's warm and running nicely, do you have good engine "braking" when you let off the throttle? or when you rev it, and let off do the rpms drop back to idle instantly or does it take it's sweet time getting down to 1000 rpm?
Both conditions would indicate a lean condition, but the plugs will tell the story best.

 

Do you have a manual?
It's pretty involved, and you need a set of feeler gauges that fit between the camshaft supports. They need to be less than 3/8" wide and start at .0015 in

If they are tight that's when it gets fun!...

 

It has very good engine braking, the RPM's drop quickly when I release the throttle. Plug color is a little on the light side of tan so it could probably stand to be a little richer.

I'm stumped trying to figure out what changes from when the engine is cold and when it is hot that would have such a dramatic effect on starting it.

Actually, I have noticed a gradual decline in ease of starting for some time now, so this isn't like the problem popped up all of the sudden. I attributed the decline to an aging battery that was turning the engine over slower. But a brand new, fully charged battery hasn't helped a bit.

 

No Sir, no manual. :cry:

 

Ok, I did the compression test and was not happy...

#1 was 80
#2 was 115
#3 was 102
#4 was 98

I put a teaspoon of motor oil into each cylinder and the numbers shot up to well over 150 in each cylinder.

This means rings right?

 

Yes usually indicates rings since wet popped way up...

 

Oh joy!

:cry:

 

The best way to to do the rings and or valve clearances is to pull the engine. That entire ensemble is a pita to get in and work with when it is in the frame. I'd check with wiseco or another company to see if they have pistons etc for the bike, or try and find another engine. If memory servers, there is an engine with 6k on ebay for 250. That sucks, but they do go when they are that old.

 

When looking at the costs, you have to include a bunch of other stuff besides the rings...Which will probably cost you $150 alone
You'll need a bunch of gaskets (about $125 or so)
You should at least lap the valves (which is cheap), but many will suggest new valve guides and seals (20 valves x $10 for each seal = $200)
Once you break the head apart, you'll need to adjust the valves so you'll need to get some shims. There are options for trading shims though!

Of course there are no guarantees that an engine off E-bay will run any better. Maybe they would guarantee it for XXX amount of compression??

And ABSOLUTELY pull it out of the frame as was said above. It comes out pretty easily actually since the right part of the frame is removable.