Ace hesitation

First topic message reminder :

Hi guys, new to the forum. Was directed here by a fellow ace owner I met at Chiswick Honda who said you guys knew your stuff when it comes to our beloved aces and cats.

I've had this problem for a while now and I can't get my head round it... my mechanical knowledge extends to the Haynes manual.... So either I've missed something or it could be something else.

What I've done to try and diagnose it -

Run through seafoam to try and get rid of any blockages (which I doubt as I also opened up the carbs to give them a quick once over and all looks clean and tidy)

Checked between the carbs and engine for any leaks.

Pulled all the coils and leads and checked their resistances (the only thing odd was the pickup coil which measured 105 ohms, but a quick call to yamaha said this shouldn't be a concern, they're only replaced if completely screwed)

I'm now at a loss, apart from taking it all apart and doing everything again but I'm not really sure.  Anyone have any ideas?

Thanks!

Hi there, have you managed to sort this out yet? I had an ace not too long ago, cracking bike! ...you mentioned the cables were 'ok' on the exup, but were you able to actually examine the valve itself? If the cover and bolts were rusted, there's a good chance the valve is seized (or partially seized). The only other way to inspect is to remove the end can and link pipe (if you can) and look through the collector box.

These valves are notorious for seizing, most people change the pipes and get rid.

Regards,

Paul

mrfrance wrote:Hi there, have you managed to sort this out yet? I had an ace not too long ago, cracking bike! ...you mentioned the cables were 'ok' on the exup, but were you able to actually examine the valve itself? If the cover and bolts were rusted, there's a good chance the valve is seized (or partially seized). The only other way to inspect is to remove the end can and link pipe (if you can) and look through the collector box.

These valves are notorious for seizing, most people change the pipes and get rid.

Regards,

Paul

Not yet, I thought I did. Pulled the plugs and they were pretty crap, so I replaced them and it seemed like it was running okay.

Then it decided it wouldn't even go above idle and left me stranded not far from work...

However as I was trying to haul the thing back to the office car park without it going past idle the rev counter started displaying a code for me intermittently... 3k - TPS. The plot thickens!

To check your tps remove tank and airbox. Tps is on right hand side of carbs. Ignition off unplug the tps and with a volt meter on ohms measure the resistance between the blue/black wires on the sensor. Slowly open and close throttle which should give you ranges from 0-5ohms give or take 1 ohm. Outside of this you need a new tps.

Also just going through manual and it says pick up coil should be between 135-165ohms at 20°C

Right, new pickup coil and new tps has arrived. I'll fit them one by one and see which one (if either) solves the issue.

Fingers crossed.

Make sure all large hammers are locked away.

Right guys, result. It's been running perfectly for two weeks now, no issues.

Thank you for all your help and suggestions which got me back on two wheels.

Seems two things were contributing to the problem. After changing the pickup coil the low end hesitation disappeared, so it's clear that that was the main issue. However there was still a dead zone in mid range power so I took another look at the exup cables one was actually snapped half way up. So that was replaced and no more issues.

Again, thank you all and I'll see you out there!

That's great news. Another saved from accidentally going up in flames.

Fantastic news, glad you managed to get to the bottom of it - frustrating non the less trying to get there though.

SteveCat wrote:Fantastic news, glad you managed to get to the bottom of it - frustrating non the less trying to get there though.

Especially as it's just when the weather decided to drop to 5 degrees!

Glad it's sorted, well done.

Paul