# Diagnostic question: Old POS Honda motorcycle. **URL:** \ **Category:** NYSpeed Automotive\ **Created:** [May 7, 2013, 7:28am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454 "2013-05-07T07:28:37Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![system](https://canada1.discourse-cdn.com/flex034/uploads/speedlife/original/2X/b/b7170c8eddc0b95ece6b88172b2f416a08489a45.png) [@system](https://forums.speedlife.net/u/system)\ **Post date:** [May 7, 2013, 5:54pm UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/21 "2013-05-07T17:54:34Z")
> [@checko](#): > > i mentioned before, check/adjust valves. my cb750 had weird backfire/popping issue and with a valve adjustment fixed the problem Fosho, feeler gauges coming out tomorrow. ---
**Author:** ![jay\_g](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jay_g/32/111288_2.png) [@jay\_g](https://forums.speedlife.net/u/jay_g)\ **Post date:** [May 8, 2013, 6:01am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/22 "2013-05-08T06:01:47Z")
If cam was off it would affect both cylinders. If valve adjustment was tight it would have issues starting and could allow blow back if the intake was tight. Switching coils and making no difference rules out electrical issues unless for what ever reason it can’t supply a strong enough spark for both cylinders. Its really sounding like a fuel issue or valve adjustment is off. If its fuel it could be lean from a air leak or the carb is not supplying enough fuel. Again try carb cleaner, while its running spray all around the intake boot and carb and see if it clears up at idle and when you rev it up. Also get new plugs, they are cheap. What does the plug look like? Are you running open filters? Is it jetted correctly? How clean is the gas tank? ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex034/uploads/speedlife/original/2X/b/b7170c8eddc0b95ece6b88172b2f416a08489a45.png) [@system](https://forums.speedlife.net/u/system)\ **Post date:** [May 8, 2013, 6:09am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/23 "2013-05-08T06:09:36Z")
-new spark plugs, I have like 5 sets sitting around. I’m pulling the right side and it’s showing fuel on the plug. -Starts and idles fine. Hits well at idle. -Carbs have been rebuilt and CLEANED, carb bowl float levels are perfect. -Gas tank is clean and I have inline fuel filters. I am really hoping and thinking that we are looking at either valve adjustment or timing. I will post results later tonight. ---
**Author:** ![focusinprogress](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/focusinprogress/32/7227_2.png) [@focusinprogress](https://forums.speedlife.net/u/focusinprogress)\ **Post date:** [May 8, 2013, 6:14am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/24 "2013-05-08T06:14:34Z")
wait. have you still not increased jet sizes? ---
**Author:** ![jay\_g](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jay_g/32/111288_2.png) [@jay\_g](https://forums.speedlife.net/u/jay_g)\ **Post date:** [May 8, 2013, 6:22am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/25 "2013-05-08T06:22:12Z")
Hopefully its just valve adjustment. I assume this motor uses rockers. Its very easy to tighten clearance on a rocker set up when you tighten up the nut. I know how frustrating this is. Many times I was ready to burn it down because of issues like this. ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex034/uploads/speedlife/original/2X/b/b7170c8eddc0b95ece6b88172b2f416a08489a45.png) [@system](https://forums.speedlife.net/u/system)\ **Post date:** [May 8, 2013, 6:25am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/26 "2013-05-08T06:25:17Z")
Yes, rockers. It’s VERY possible that the valves are too tight. I am remembering in the fall when focusinprogress came over with feelers before putting it away for the winter. We focused primarily on the carbs at the time but spent a bit popping the valve cover and I remember him saying that they were tight. I think. Nick, ringing a bell? ---
**Author:** ![focusinprogress](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/focusinprogress/32/7227_2.png) [@focusinprogress](https://forums.speedlife.net/u/focusinprogress)\ **Post date:** [May 8, 2013, 6:30am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/27 "2013-05-08T06:30:03Z")
> [@maxwell](#): > > Yes, rockers. It’s VERY possible that the valves are too tight. I am remembering in the fall when focusinprogress came over with feelers before putting it away for the winter. We focused primarily on the carbs at the time but spent a bit popping the valve cover and I remember him saying that they were tight. I think. Nick, ringing a bell? I don’t recall. the amount of bikes I’ve worked on in the last 3-4 months is seriously rediculous hahahaha. If you haven’t bumped up jet sizes yet…DO THAT. you could be doing more harm then good continuing to try to track down an issue if it’s super lean. ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex034/uploads/speedlife/original/2X/b/b7170c8eddc0b95ece6b88172b2f416a08489a45.png) [@system](https://forums.speedlife.net/u/system)\ **Post date:** [May 8, 2013, 8:06am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/28 "2013-05-08T08:06:36Z")
> [@focusinprogress](#): > > I don’t recall. the amount of bikes I’ve worked on in the last 3-4 months is seriously rediculous hahahaha. If you haven’t bumped up jet sizes yet…DO THAT. you could be doing more harm then good continuing to try to track down an issue if it’s super lean. Main jet is bumped up one, pilot and slow are stock. Plugs aren’t burning white at this point. I don’t think im doing any real harm at this point outside of the current right cyl issue. ---
**Author:** ![focusinprogress](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/focusinprogress/32/7227_2.png) [@focusinprogress](https://forums.speedlife.net/u/focusinprogress)\ **Post date:** [May 8, 2013, 8:19am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/29 "2013-05-08T08:19:30Z")
> [@maxwell](#): > > Main jet is bumped up one, pilot and slow are stock. Plugs aren’t burning white at this point. I don’t think im doing any real harm at this point outside of the current right cyl issue. based on that info, I would agree. ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex034/uploads/speedlife/original/2X/b/b7170c8eddc0b95ece6b88172b2f416a08489a45.png) [@system](https://forums.speedlife.net/u/system)\ **Post date:** [May 9, 2013, 8:07pm UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/30 "2013-05-09T20:07:35Z")
Timing was off. Bike runs like a raped ape now. I’m pumped! It’ll be registered and on the road next week. Just need to make a seat pan and button up a few more loose ends! ---
**Author:** ![jay\_g](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jay_g/32/111288_2.png) [@jay\_g](https://forums.speedlife.net/u/jay_g)\ **Post date:** [May 10, 2013, 5:16am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/31 "2013-05-10T05:16:53Z")
Glad you figured it out. How bad was it off? I’m surprised it didn’t affect both cylinders. Did you touch the top end at all since you’ve owned it? ---
**Author:** ![JayS](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jays/32/15375_2.png) [@JayS](https://forums.speedlife.net/u/JayS)\ **Post date:** [May 10, 2013, 5:25am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/32 "2013-05-10T05:25:42Z")
:tup: ---
**Author:** ![system](https://canada1.discourse-cdn.com/flex034/uploads/speedlife/original/2X/b/b7170c8eddc0b95ece6b88172b2f416a08489a45.png) [@system](https://forums.speedlife.net/u/system)\ **Post date:** [May 10, 2013, 7:59am UTC](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454/33 "2013-05-10T07:59:03Z")
[quote=“jay\_g,post:31,topic:230454"”] Glad you figured it out. How bad was it off? I’m surprised it didn’t affect both cylinders. Did you touch the top end at all since you’ve owned it? [/quote] No but we checked the valves and they are in spec. Bikes running so well! Timing was off a bit, but honestly we just took it all down, ensured the advance weights were working, lubed everything up, regapped the points, and adjusted the timing a bit. It was enough to REALLY make a difference. It idles perfect, revs like a motherfucker, and starts first kick. Super pumped. [Previous page](https://forums.speedlife.net/t/diagnostic-question-old-pos-honda-motorcycle/230454.md?page=1)