Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Managed to get my Urban Express running - after cleaning the carb, replacing the head gaskets, etc. It use to do 27mph (AX31 belt) but after doing all the cleaning+replacing its now only maxing out at 20mph. Any suggestions on what I might have missed. Dont want to buy any upgrades if possible.

Thanks

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

My first thought is..... What cylinder is on it, factory 49cc?? If aftermarket, is decomp leaking at gasket? Spark plug sealing? Whats your compression?

Are crankshaft seals good? Has your petcock become your main jet? let gas flow into jar and see if it slows down enough to cause problems (very common). Are u Sure you have a good fuel filter and no boogers got in carb?

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

factory cylinder

spark plug is tight - no seals

dont have any tools to check compression - there doesn't seem to have any air/ oil leaks.

what do you mean by crankshaft seals? the part where the piston attaches to? the rings on the piston are new, piston and cylinder are in good working condition

theres good flow from the petcock - its brand new - http://www.pedparts.co.uk/product/1427/motoforce-racing-fuel-filter

it was leaking before from the carb to the manifold (screws are tight) - but fixed that now - wasn't running/ idling properly when it had this issue

just a bit confused as it lost quite a bit of speed - i thought cleaning/ replacing new parts would at least add some more power no lessEdited 1 time(s). Last edit at 12/28/17 09:06AM by crillz666.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

I read ur other post and watched the video.

The top ring on the piston can be put on upside down(find some images read about it) did the cylinder get honed? My opinion is you have a compression issue. Is the cylinder head flat? They can warp over time and could leak even with a new gasket. Although unlikely.

I suggest finding a compression tester to borrow..

The crankshaft seals I was speaking of......One is behind the flywheel/generator and the other is behind the variator, quite a chore to change them. If they leak you will have never ending problems.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Also, one time I spent a few hours scratching my head trying to diagnose a Honda and found that some type of insect had built a mud cocoon in the tip of the exhaust overnight, It was just like concrete and had to be drilled out.

Just a thought, Is your muffler free flowing?

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

nothing clogging the exhaust... :)

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Captain Janeway /

Still have any gas leaks? makes me think your float needle not seating right since you mentioned it. You may want to clean the carb again, check for air leaks at carb and everywhere on that top end since it sounds like you had it open. (see Fred's guide in wiki). Make sure your exhaust pipe is seated properly at the cylinder base. Yes, get that compression checked too.

You change anything else? All stock at this point? It should be running about 30 mph for you (unless it's an Iowa model)

Good luck!

Fred;s

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Baron Von Hamilton /

If you had air leaks it may have been going faster caus it was lean. Which was not good for the motor.

Are you going by the spedo on the bike? If so, you may still be going the same speed and the cable or tach is messed up.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Jack Rutherford /

similar thing happened to me. it ran rich after cleaning the carb and 4 stroked at full throttle.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

> Jack Rutherford Wrote:

> -------------------------------------------------------

> similar thing happened to me. it ran rich after cleaning the carb and 4

> stroked at full throttle.

I pondered the same thing.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Baron Von Hamilton /

I thought that also.....I once bought a dirt bike that the previous owner “cleaned the carb real well”. It 4stroked on the top. I ordered new jets and it was back to running strong. You can try replacing the jet with the same size one and see what happens.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

> Baron Von Hamilton Wrote:

> -------------------------------------------------------

> I thought that also.....I once bought a dirt bike that the previous

> owner “cleaned the carb real well”. It 4stroked on the top. I ordered

> new jets and it was back to running strong. You can try replacing the

> jet with the same size one and see what happens.

That might be a good idea . It wouldn't be the first time some wanna be has drilled a jet .

FYI : once a jet is drilled , the original flow design becomes a straight through passage .

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

UPDATE - so I can get to 23/24mph now (but thats feather the throttle). I do think its what you guys have said - that its four stroking. It sounds different when I fully turn the throttle. I rode it for 20miles - cut the engine - went to turn it back on after a few minutes and its struggling to go pass 20mph. After maybe 30mins the speed gradually came back. As I took the bystarter - you think its making the mixture too rich (like more air in). One of the holes (intake manifold) that use to be attached to the bystarter is wide open - you think getting a smaller main jet could help.

I'm gonna try and post a video to show how its sounding.Edited 1 time(s). Last edit at 12/31/17 06:26PM by crillz666.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Captain Janeway /

Post some photos. I can't tell from the last post if you're saying you have unattached hoses.

Did you re-clean the carb? Any gas leaking (float needle problem)? could you have made your main jet bigger while cleaning if you used a wire, etc? Treats having a sale. The two stock sizes are 70 and 85 (I guess the 70 is for the Iowa model). All of mine have started with an 85.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

More air in is lean, not rich. You can try to take the air box off and see if performance improves or actually gets worse. That is a real quick way to try and determine a lean or rich condition.Edited 1 time(s). Last edit at 01/01/18 08:28AM by ihazvalves.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

When its straight - I'm flat out on the throttle. You can hear the change in sound.Edited 1 time(s). Last edit at 01/01/18 11:57AM by crillz666.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Brandon Weiss (aka B-Man) /

> W L Wrote:

> -------------------------------------------------------

>

>

> When its straight - I'm flat out on the throttle. You can hear the

> change in sound.

Yes, that is indeed 4 stroking.....but its not bad. Your jetting is extremely close, assuming theres nothing else wrong with the bike (seals, leaks).

Seems to run great, just drop 1 or 2 jet sizes.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

There only seems to be an 84, 82 jet size... so might get these and see.

http://www.pedparts.co.uk/product/710/single-gurtner-jets

You can also notice when I'm at a red light or at a stop... I'm reving the engine a bit to help with acceleration - if I dont do this it takes me 3-4 seconds to get moving.

These are the holes where the bystarter hoses use to be attached.

This hole (intake manifold) is the one where if I cover it with my finger the engine dies...

Edited 2 time(s). Last edit at 01/01/18 12:15PM by crillz666.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

I cleaned the carb - was pretty clean anyway when I opened it. Float needle seems fine. Cleaned the jet with carb cleaner - no wires.

> Captain Janeway Wrote:

> -------------------------------------------------------

> Post some photos. I can't tell from the last post if you're saying you

> have unattached hoses.

>

> Did you re-clean the carb? Any gas leaking (float needle problem)? could

> you have made your main jet bigger while cleaning if you used a wire,

> etc? Treats having a sale. The two stock sizes are 70 and 85 (I guess

> the 70 is for the Iowa model). All of mine have started with an 85.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Brandon Weiss (aka B-Man) /

What jet do you have in there right now?

Also, from the pictures it does not look like you really cleaned the carb, its filthy. You want it spotless both inside and out.

You need to dissasemble the carb entirely and clean every passage thoroughly, compressed air and a fine wire from a wire brush work great.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

well it rained here in london so its quite dirty right now :( ... I did clean the carb - inside and out - it looked brand new

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Captain Janeway /

Try Ryan's suggestion of pulling the airbox for a run. It does sound like it's four stroking.

I'm guessing you don't want to use your choke so that's why all the hoses are off, but at least cap them to keep the dirt out.

I may have missed it, but injector or premix? If injector, is that index mark lined up? Maybe you're dumping too much oil in.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

I'll try without the airbox tomorrow and see what the effect is.

My bystarter unit was incomplete so I basically removed all of it. I might cap the other two holes - and put some tights or mesh on the other one. It won't run if the hole in the second picture is capped.

I just put 2 stroke oil straight into the oil tank - I dont mix it.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

The hole in the second picture is a DIRECT opening to your intake, and is a massive vacuum leak. It's a miracle the bike is running at all, and will be running very lean as such. Your idle adjustments may be so far off just to make the engine run that when you cap it the bike dies. What setting is your idle/air screw at (# of turns out from lightly seated in)? That nipple is the only one that MUST be capped, as it provided vacuum to the entire choke system and allowed it to operate.

Knowing now the state of chaos that your fueling system is in, we can narrow down what is happening. Unless you are actually running so rich that the air leak offsets that enough to run then I would say you may have your settings too far off to run when there isn't a huge leak. Or if that nipple was always open maybe someone put a much larger jet in, but I don't think you could get a jet large enough for that carb (96 is biggest) to make that work. Maybe it was drilled out. Pull the Main jet our and get a really good and clear picture of the orifice up close.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

I've ordered some new jets - 84 and 82. I'll take some photos of the current one in the carb once they arrive. I'll make a note of the number of turns.

Also anyone what the phenomenon is called whenever I max out - the engine loses power. This also happens when I go down hill. I try and pull back on the throttle so it can gain power again or pull over-stop. After running it today the acceleration seems to be better.

Also if anyone has the black part on the bottom left - thats the part I need to complete the whole bystarter system. I'll also be interested in buying everything as well.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Dude stop running the bike with that intake leak. You are either fouling the plug at full throttle and cutting out, or the bike is going so lean you aren't making power. Either way the fuel mixture is drastically off. You stand very good chance to do permanent damage to the piston and cylinder.Edited 1 time(s). Last edit at 01/02/18 03:19PM by ihazvalves.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

ok thanks

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

i agree with what DPC ryan says. u have a massive air leak. patch that shit up before changing ANYTHING on that carb. tuning at this point is dangerous and a waste of time.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

Captain Janeway /

Let me see if I have one. Listen to Ryan. Do you have hoses and the choke? If you string hose make sure it's heavy duty and doesn't brush against head and melt.

Re: Honda Urban Express - Lost 7mph - its now doing only 20mph max?

can you convert that to a manually operated choke?

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