Author Topic: 2nd gear feels like it's not getting gas at high rpms (Read 4966 times)

bookah · « **on:** November 29, 2015, 11:00:57 PM »

Title. All other gears feel fine, when in 2nd and in the upper band the engine feels like it just isn't getting gas. Anyone know what this is all about?

70CB750 · « **Reply #1 on:** November 30, 2015, 04:23:00 AM »

Could it be the gear dogs?

flybox1 · « **Reply #2 on:** November 30, 2015, 07:06:34 AM »

positive it isn't a jetting issue?

Don R · « **Reply #3 on:** November 30, 2015, 07:08:49 AM »

Just guessing but could the floats be set low and in second when it's pulling hard the fuel is running up the back of the bowl?

70CB750 · « **Reply #4 on:** November 30, 2015, 07:11:35 AM »

Usually the 3rd gear seas the hardest acceleration, if it starves for fuel, that's where I would expect issues.

bookah · « **Reply #5 on:** November 30, 2015, 10:01:29 AM »

Quote from: Don R on November 30, 2015, 07:08:49 AM

Just guessing but could the floats be set low and in second when it's pulling hard the fuel is running up the back of the bowl?

I think you might be right. This morning I had a really hard time kicking her over. Sparks firing, gas flowing to bowls, compression is fine. My guess is the floats are set wrong and it's having a hard time sucking anything up. Once I kicked it over I had no problem kicking it over again, but getting that initial grab was like pulling teeth.

flybox1 · « **Reply #6 on:** November 30, 2015, 10:10:06 AM »

clear tube test, asap.

bookah · « **Reply #7 on:** November 30, 2015, 11:09:57 AM »

Quote from: flybox1 on November 30, 2015, 10:10:06 AM

clear tube test, asap.

What's this?

bookah · « **Reply #8 on:** November 30, 2015, 11:32:38 AM »

Quote from: flybox1 on November 30, 2015, 07:06:34 AM

positive it isn't a jetting issue?

Well the jets were working perfectly. I recently replaced the carb bowls but I didn't touch the floats or jets. Now this.

flybox1 · « **Reply #9 on:** November 30, 2015, 11:39:43 AM »

Quote from: bookah on November 30, 2015, 11:32:38 AM

Quote from: flybox1 on November 30, 2015, 07:06:34 AM
positive it isn't a jetting issue?

Well the jets were working perfectly. I recently replaced the carb bowls but I didn't touch the floats or jets. Now this.

by "jetting issue' i mean your air/fuel mixture could be off, lean or rich, and giving you no throttle response.
doesnt mean your jets are bad, just incorrect for that throttle position. Fuel starvation maybe?
the clear tube test is used to see what the fuel level is inside your carb bowls.
too high and you'll run rich, to low and you'll be lean.

http://forums.sohc4.net/index.php?topic=149299.0

Deltarider · « **Reply #10 on:** November 30, 2015, 11:45:07 AM »

Quote

My guess is the floats are set wrong

Why would a PO or anyone else set the floats wrong?

flybox1 · « **Reply #11 on:** November 30, 2015, 11:50:59 AM »

Quote from: Deltarider on November 30, 2015, 11:45:07 AM

Quote
My guess is the floats are set wrong

Why would a PO or anyone else set the floats wrong?

Because if it isn't broken, they HAVE to fix it

bookah · « **Reply #12 on:** November 30, 2015, 11:51:23 AM »

Quote from: flybox1 on November 30, 2015, 11:39:43 AM

Quote from: bookah on November 30, 2015, 11:32:38 AM
Quote from: flybox1 on November 30, 2015, 07:06:34 AM
positive it isn't a jetting issue?

Well the jets were working perfectly. I recently replaced the carb bowls but I didn't touch the floats or jets. Now this.
by "jetting issue' i mean your air/fuel mixture could be off, lean or rich, and giving you no throttle response.
doesnt mean your jets are bad, just incorrect for that throttle position.
the clear tube test is used to see what the fuel level is inside your carb bowls.
too high and you'll run rich, to low and you'll be lean.

http://forums.sohc4.net/index.php?topic=149299.0

Perfect thanks. Can I run the tube off the overflow drain, or does it have to be in the drain screw hole?

flybox1 · « **Reply #13 on:** November 30, 2015, 11:56:37 AM »

read the thread i linked.
your carb type determines where your tube connects.

bookah · « **Reply #14 on:** November 30, 2015, 11:58:51 AM »

Quote from: flybox1 on November 30, 2015, 11:56:37 AM

read the thread i linked.
your carb type determines where your tube connects.

Ah, yea PD carbs. Thanks!

flybox1 · « **Reply #15 on:** November 30, 2015, 12:21:42 PM »

Quote from: bookah on November 30, 2015, 11:58:51 AM

Ah, yea PD carbs. Thanks!

The best kind. @overflow tubes - makes this test a cinch!

Don R · « **Reply #16 on:** November 30, 2015, 01:06:23 PM »

My PO bent up the float tabs and drilled the jets. Who can say why I bet it's the same reason one put a huge 55/65 watt halogen headlight bulb in a 6 volt CL100

Don R · « **Reply #17 on:** November 30, 2015, 03:06:31 PM »

Could it be you're just snapping the throttle open too fast and hitting the flat spot caused by a lack of accelerator pumps?

Redline it · « **Reply #18 on:** November 30, 2015, 04:05:46 PM »

I would just remove second gear from the trans.

goldarrow · « **Reply #19 on:** November 30, 2015, 04:10:51 PM »

Let me take it out for a test ride for ya

harisuluv · « **Reply #20 on:** November 30, 2015, 04:19:16 PM »

I can't really think of a reason why the fuel system would be responsible for something only happens in 2nd gear. Not saying it's not possible--just trying to think of logically why that would be the case.

70CB750 · « **Reply #21 on:** November 30, 2015, 04:29:36 PM »

Quote from: harisuluv on November 30, 2015, 04:19:16 PM

I can't really think of a reason why the fuel system would be responsible for something only happens in 2nd gear. Not saying it's not possible--just trying to think of logically why that would be the case.

My money is on the transmission, 2nd gear is notorious for wearing out first.

harisuluv · « **Reply #22 on:** November 30, 2015, 04:31:04 PM »

Aw, that would be a bummer. I'd rather wrestle the carbs on and off 2-3 times with hard boots than have to split the cases

Kenzo · « **Reply #23 on:** November 30, 2015, 05:48:11 PM »

Quote from: bookah on November 30, 2015, 10:01:29 AM

Quote from: Don R on November 30, 2015, 07:08:49 AM
Just guessing but could the floats be set low and in second when it's pulling hard the fuel is running up the back of the bowl?

I think you might be right. This morning I had a really hard time kicking her over. Sparks firing, gas flowing to bowls, compression is fine. My guess is the floats are set wrong and it's having a hard time sucking anything up. Once I kicked it over I had no problem kicking it over again, but getting that initial grab was like pulling teeth.

If the bowls were low I would expect a definite stumble not just feeling of being low on power.

~5,500 to ~8,500 is the sweet spot for producing power...how high are you revving it? The power does drop off when approaching redline. When I get on it hard second gear runs out real quick and reach for third.

It does not sound like a transmission problem.

Cheers,
Kenzo

bookah · « **Reply #24 on:** November 30, 2015, 06:31:24 PM »

I am just at a complete loss. I rode it home from work. Kicked over first kick, shifts perfectly. No gear slippage, getting gas all gears no matter how high I take the rpms. Im thinking the fuel issues solved itself (this was only the second rode since I finished the rebuild on thurs) ...then a whole new issue springs up.

I pull into my driveway after the 20ish mins home and the bike dumps about 1/4 qt of oil right when I pull in. Never had leak issues in the past. No oil where I park it at work or where I park it at home. Wtf. And I can't even tell where it came from since the whole bottom is oily. I haven't touched the engine, no bolt tightening, nothing. It rode just fine when I finished the rebuild of the bike except for the above mentioned fuel issue (which, to answer some further questions here, simply felt like the bike was running out of gas when I was in the upper rpms of 2nd).

It seems I can't escape issues. Everything that could go wrong, will.

harisuluv · « **Reply #25 on:** November 30, 2015, 07:50:28 PM »

When you say "rebuild" what exactly do you mean by this, did you just do an engine rebuild?

goldarrow · « **Reply #26 on:** November 30, 2015, 08:01:50 PM »

Oil leaking could be from badly leaking shifter seal, but wouldn't know for sure until open up the shifter cover

bookah · « **Reply #27 on:** November 30, 2015, 08:13:14 PM »

Quote from: harisuluv on November 30, 2015, 07:50:28 PM

When you say "rebuild" what exactly do you mean by this, did you just do an engine rebuild?

I left the engine alone. I completely stripped bike to frame and rebuilt it.

bookah · « **Reply #28 on:** November 30, 2015, 08:14:53 PM »

Quote from: goldarrow on November 30, 2015, 08:01:50 PM

Oil leaking could be from badly leaking shifter seal, but wouldn't know for sure until open up the shifter cover

I'm going to go work on it for a bit tonight and see what I can discover. Thanks for the tip goldarrow! I swear I didn't touch anything this time

bookah · « **Reply #29 on:** November 30, 2015, 09:16:36 PM »

K. Shifter cover off. There was a tablespoon- ish of oil in there, but no obvious leak. If it was the shifter seal, would it be actively weeping even with the oil cold?

goldarrow · « **Reply #30 on:** November 30, 2015, 09:18:13 PM »

Shifter seal is available from Honda about $4 I think

bookah · « **Reply #31 on:** November 30, 2015, 09:30:04 PM »

Well. I think I figured this out, but I have to ride it tomorrow to make sure. This may sound silly, but:

I think all the oil that dumped out my shifter cover was oil leftover from my accident that spilled out the engine breather back in August. Im not sure how it managed to stay in there all this time, but I checked my oil level, and it's reading full. I can't find a leak despite cleaning up all this oil. I lost a lot of oil out the breather tube when I went down, some of it probably found it's way inside the shifter cover and spilled out given the angle of my driveway.

At worst it's the shifter seal, at best it's my above guess. What a wierd thing to happen.

Regardless, ill update tomorrow

Redline it · « **Reply #32 on:** November 30, 2015, 11:15:58 PM »

Quote

I think you might be right. This morning I had a really hard time kicking her over. Sparks firing, gas flowing to bowls, compression is fine. My guess is the floats are set wrong and it's having a hard time sucking anything up. Once I kicked it over I had no problem kicking it over again, but getting that initial grab was like pulling teeth.

If the bowls were low I would expect a definite stumble not just feeling of being low on power.

~5,500 to ~8,500 is the sweet spot for producing power...how high are you revving it? The power does drop off when approaching redline. When I get on it hard second gear runs out real quick and reach for third.

It does not sound like a transmission problem.

Cheers,
Kenzo
[/quote]How high, reving it? Power drops off approaching redline?

bookah · « **Reply #33 on:** December 01, 2015, 09:18:55 AM »

Quote from: Redline it on November 30, 2015, 11:15:58 PM

Quote
I think you might be right. This morning I had a really hard time kicking her over. Sparks firing, gas flowing to bowls, compression is fine. My guess is the floats are set wrong and it's having a hard time sucking anything up. Once I kicked it over I had no problem kicking it over again, but getting that initial grab was like pulling teeth.

If the bowls were low I would expect a definite stumble not just feeling of being low on power.

~5,500 to ~8,500 is the sweet spot for producing power...how high are you revving it? The power does drop off when approaching redline. When I get on it hard second gear runs out real quick and reach for third.

It does not sound like a transmission problem.

Cheers,
Kenzo

How high, reving it? Power drops off approaching redline?
[/quote]

Yea it is definitely a gas problem. Although it hasn't happened in the last few rides, so I'm waiting it out to see if it resurfaces. Essentially I'd hit anywhere above 4,500 in 2nd and the engine would stumble really hard (exact same feeling like if you've ever run out of gas on the bike or even in a car), burping, choking, coughing, whatever you want to call it. Then I'd shift into 3rd and perfectly fine. If it starts happening again I will report back.

bookah · « **Reply #34 on:** December 01, 2015, 09:21:00 AM »

Also, rode the bike into work today, ~20ish minutes, no oil came off it. I only briefly looked under the bike when I parked it to see if there was anything weeping (or pouring) out from under the shifter cover, nothing. Fingers crossed that my guess was right.

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Author Topic: 2nd gear feels like it's not getting gas at high rpms (Read 4966 times)