P700 [SOLVED] Hard start, high compression, running lean, killing starters

[fmjnax]

I have an '11 Big Red MUV700 (P700 engine) that I've been working on fixing up. It had an extremely rough life before I got it. Currently, the machine overall runs great when it's running.

A few months ago I had the engine out and completely tore it down and rebuilt it. It got a new camshaft, followers, timing chain, tensioner, cylinder, cylinder head, piston, rings, gaskets, valves, valve seals, battery, starter, some sensors, and probably some other small things I'm forgetting. Basically, a fresh overhaul. Of course I made sure to set the timing and valve clearances. I'm no stranger to rebuilding small engines.

However, since I overhauled it, it has been hard to start when the engine is "cold". We have to give it about 1/4 - 1/2 throttle while cranking to get it to fire. No amount of key cycling seems to affect it. Once it does fire, it runs great. If you kill it and then immediately crank it back up, it fires up almost immediately. As the engine cools down, it gets harder to start. It didn't do this before I overhauled it so I'm almost certain it's something I did (or didn't do).

Since then, I have been going through a starter every couple of weeks. I can swap one out in about 10 minutes now. LOL! What happens is that all the cranking causes the teeth on the starter to chew down to where it won't engage anymore. I just carry a spare and the tools needed to make the swap.

Yesterday I decided to throw a new spark plug at it to see if that was the issue since I hadn't done that and it was terribly fouled from how it used to run. No luck with that being the issue, but this morning when I was working on it I pulled the new spark plug (NGK BK5RE-11) and the tip was as white as could be! Looks like I have a lean condition (engine doesn't overheat, no smoke, doesn't run rough at all). The plug has about 5 hours on it.

Since I had the plug out, I ran a compression test. I get 90psi every time (and calibrated my meter against a regulated air supply so I know it's accurate). The manual states 80psi is spec, so I'm a bit high here.

No MIL light (so I assume no DTC's, but I don't have an HDS reader).

Here's what I'm thinking the culprits could be, given that I overhauled it:
- I may not have timed the machine 100% correctly. If it's off, it's only going to be 1 tooth, MAYBE 2, off. I KNOW I was on TDC on the correct stroke when I timed it, but with the angle of the engine it might not have been lined up properly.
- I may not have set the valve clearances correctly (or they settled looser/tighter), especially the exhaust valves (which DO impact the compression/decompression)
- Probably need to clean the air filter, though I don't think that's the culprit

I'm going to get started on checking those two things, but wanted to get this out here and see what else I might want to look in to. Any thoughts?

 

[Admin]

 

[highpocket74]

I'm learning about these 700 engines having bought a used 16 P700 last month. It was running but smoking terribly bad. We put a whole new all Honda topend on it and it ran great for a while. Now it won't idle! Changed the IAC thing with no improvement. Next part will be the TPS. This machine has been a total pain. I've got too much in it now to quit. Same here, no MIL codes.

 

[Mopower58]

Correct thickness head gasket?

 

[fmjnax]

I'm in the same boat, highpocket74. I got this machine for next-to-nothing as it was all tore up and not running. Once I got it running, it was smoking like a chimney and ran rough. The overhaul fixed that, but now I'm on to the issues in this post. Still have to work on the chassis and body. Some days (like today), I'm ready to throw in the towel, but I'm too hard-headed and it has actually been an enjoyable project/hobby. I WILL get it all running correctly eventually.

I'm pretty sure it's the correct gasket, Mopower58. It's an OEM gasket set and was brand new.

 

[highpocket74]

My gasket came from Honda too.

My father-in-law is my mechanic and this machine is driving him crazy! He's learning too! Very frustrating though.

It runs great in the midrange but won't idle and won't run wide open. It's never run wide open which now leads me to think TPS is going bad and getting worse quickly.

 

[DRZRon1]

Timing or compression release

 

[fmjnax]

DRZRon1, the compression release is the decompressor on the cam, right? I replaced the cam with the overhaul, but went with a Caltric instead of OEM. When I replaced it, the lobes were nearly rounded instead of egg-shaped. The Caltric one still looks as new as when I put it in. I'll run through the check procedure on it when I re-time it, though. May as well since I'm already there.

 

[DRZRon1]

full transparency - haven't had a 700 apart but pics look like a centrifugal compression release? you have the old worn out cam by chance?

ive fixed a couple of small engines and either timing, bad centrifugal compression release, bent lifter rod, valves out of adjust, etc.i do know these are hard on the starter when cold - seem some ingenious members just add a small second battery in series and zap it with 24V - but lets not go nuts here - should be able to rotate that engine and watch the valves when cold and see if the exhaust valves bumps a little before opening.

 

[Mudwisel]

My first thought would be valve tran timing(combustion)

 

[Jerryg]

Fuel issue.

 

[fmjnax]

I’m thinking timing as well guys. 😄 Tore it down and gave it a check. I put it at TDC and checked the cam. I didn’t bother setting it at the compression stroke since I’m redoing it so the picture is 180 degrees out, but if you imagine the chain sprocket being rotated 180, it’s clear that it’s off at least a couple of teeth.

A question I have always wondered: When you guys time these engines, do you do the line alignment BEFORE you release the tensioner hold or after the tensioner has put the chain back under tension? The difference is minimal, but I've noticed that the tensioner will pull the sprocket clockwise just a smidge (like MAYBE a 1-tooth difference) after releasing the hold.

I do actually still have the original worn out cam. When I check the decompressor on my current cam, I’ll compare with the original and see if there are any differences. The 24V helper is an interesting thought. When I replaced the battery, I decided to do a little modification to where I could fit an actual small automotive battery. I think I'm running a 550CCA in it now. The extra voltage could help, though. Once I get this thing running solid, if I still have hard start I might look at that idea.

Jerry - I thought fuel issue at one point as well. I removed and cleaned the injector. The fuel delivery is on-spec with what the manual says. Starting fluid doesn't seem to change the condition, nor does the amount of times I "prime" with the key. Gas is fresh. I've tried 87 octane up to 93 octane with no change to the condition.

 

[Jerryg]

Jerry - I thought fuel issue at one point as well. I removed and cleaned the injector. The fuel delivery is on-spec with what the manual says. Starting fluid doesn't seem to change the condition, nor does the amount of times I "prime" with the key. Gas is fresh. I've tried 87 octane up to 93 octane with no change to the condition.

View attachment 424247 View attachment 424248

It's hard to believe it ran well once you got it running, but it's possible.

 

[fmjnax]

It's hard to believe it run well once you got it running but it's possible.

Considering the shape it was in when I got it, it's quite possible that my interpretation of "runs well once started" isn't actually as well as it should run. I don't really have a "good" baseline to go by with this machine. However, when it does fire up, it never skips a beat. It'll run 43mph (GPS) down the road, drives well at any throttle position, hits all 3 gears smoothly; up and down, no smoke, no backfire, no stutter or hesitation, doesn't seem like it's lacking any power, idle RPM within spec, no ticking/knocking. If I was going to look at buying this machine and it was already running when I took a test drive, I wouldn't think anything was wrong with it. So if this thing ends up running better after getting it all dialed in, I'm going to be quite happy!

 

[Mudwisel]

Usually you will have the slack on the tensioner side

 

[fmjnax]

The cam (and decompressor) passed spec so I think I am good there. I’ve got a dilemma on the timing, though. I am 100% on TDC without any doubt yet it is impossible to get the camshaft markings to line up. It’s like it is 1/2 tooth off. I have two options to go with: A or B? A looks closer to me and is what I currently have it set to.

 

[Mudwisel]

b

 

[Jerryg]

B looks better but, is it a new chain and gear?

 

[fmjnax]

Would you guys mind explaining why B looks better to you? For education purposes.

The chain is newer. It’s been on for about 3 months. Was new OEM then, though. Gear is old.

 

[Jerryg]

Would you guys mind explaining why B looks better to you? For education purposes.

The chain is newer. It’s been on for about 3 months. Was new OEM then, though. Gear is old.

If the idea is to line up the cam marks even with the top of the cylinder head, it looks closer to correct.

 

[fmjnax]

Ohhh, were you looking at the lines on each side? I have been referencing the single line at the bottom. Looking at the side lines, I agree, B looks much better!