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Author Topic: Am I the Pontius Pilate of this CX500?  (Read 22491 times)

Offline Odontologist

  • Posts: 176
  • Umina Beach, Australia....Where does that part go?
Re: Am I the Pontius Pilate of this CX500?
« Reply #220 on: Jul 23, 2019, 00:53:45 »
I've been having problems with my trial test rides around the block. Idles fine, but as soon as I give it throttle, it clogs down, as though it wasn't getting enough fuel. As soon as I let go the throttle to lower RPM, it's OK. Haven't been able to get past 4000 RPM. I knew, or at least, thought I knew I had rust in the tank, because when I moved it about I could hear a "slosh...slosh" with a definite feel of something scraping, like sand. It made sense, as the bike had been sitting in PO's shed for 19 years before I got it, and then another 2 in mine. Looking inside however, it looked pretty sound where I could see. The flow out of the petcock was slow and sometimes intermittent, so it had to be rust particles. I cleaned the petcock and tested it..flow was OK. I pulled apart the carbs....again...clean as a whistle.

Today I was determined to clean and fix the rust problem once and for all. I tried rinsing with distilled water several times and emptying...the sloshing continued. I gave up and hooked up a clear tube to a suction motor and separator I have, hoping to see what came out from the bottom of the tank......and this came out:



Now, some of the skeptics on here may looking in my direction, but I can assure you I DID NOT put that in the tank. After I got it I rode it once around the block. Never put fuel in. Removed the tanks and in storage until the recently for painting.

Have to put the carbs back together, fit them, and take for another run....see if that WAS the problem. Maybe yes....maybe not.

Cheers.
1982 Honda CX500 Roadster build

Offline crazypj

  • Posts: 13467
  • Split personality, I fake being smart
Re: Am I the Pontius Pilate of this CX500?
« Reply #221 on: Jul 25, 2019, 20:48:08 »
Seems you have the dreaded 3 jet CV carbs problem. It is very common when stock air-box is removed. Unfortunately, I have no idea how to fix it as the carbs use different circuitry compared to the earlier CV carbs on CB350~CB500T and do not respond to the modifications I do on them. Fitting the original air box trumpets helps
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline Odontologist

  • Posts: 176
  • Umina Beach, Australia....Where does that part go?
Re: Am I the Pontius Pilate of this CX500?
« Reply #222 on: Jul 26, 2019, 08:32:51 »
Thanks crazypj... can't do that. Need to stick to concept. I'll  just have to fiddle with them until they work. Keep you posted.
1982 Honda CX500 Roadster build

Offline Odontologist

  • Posts: 176
  • Umina Beach, Australia....Where does that part go?
Re: Am I the Pontius Pilate of this CX500?
« Reply #223 on: Aug 04, 2019, 03:59:42 »
Trap for young (and not so young) players (Long post-sorry. Lot's to say and show)

I've been trying to get this bike running, but all I've managed is to run into problems.

I solved the usual "plastic bag in the tank" problem, so I was getting good flow out of the fuel tap. _/
I then had problems with the bike stumbling at around 4200 RPM, like running out of fuel or air. I made the assumption that my carbs were not as clean as I though, so I pulled them apart again and cleaned them...again. Turns out that the Penetrol I had painted them with sipped into a few crevices. What an IDIOT! Cleaned them throughly...again.  In the process I broke a plastic non adjustable float that I was trying to adjust. Luckily I have a spare set of carbs for parts. Save.



Went out for a run and as soon as I opened the throttle the revs went up to around 4000 RPM and would not go down. When I rebuilt carbs the first time I followed Larry Cargill's carb book faithfully. I then had to pull them apart to clean the Penetrol paint that had sipped in and caused the slides to stick. When I put them together I DID NOT follow the book of Larry. I reassembled the bowls and top covers, so I couldn't sit them on the bench to align them properly, so I eyeballed it. They were not well aligned and one or both butterfly valves were sticking open.
I pulled them apart again and this time followed The Good Book....and problem solved.

Today I was able to do a few short runs around the block to dial pilot screws correctly, but it's bogging down as rpm goes up. Again gets up to 4200RPM and bogs down.  I tried removing the tank cap in case the vent was blocked. Nope. Check the float levels. Good. WTF ?

I sat in my garage, just looking at the bike for a long time, thinking that after all I've done, I've failed to make the grade. As a novice builder, If I can't get a bike to run, then it's all over. I tried everything I could think off. I knew it was a carb problem but I just couldn't understand what.

Then, just as I was about to walk away, dejected, disheartened and beaten, a thought.....I wander.....Lets give it a go !

My original fuel tap has no filter, so to avoid contamination into carbs, I put an inline filter.





I wondered if the kink in the hose might be restricting fuel flow, especially as revs go up. So I replaced it with just a length of hose and no filter.



Took it for a run, and stumble gone.  I'M BACK!

Closing anecdote: I was so happy that I just kept going around the block, until I ran out of fuel about 500m from home, and had to push the bike home. Who cares.

Anyway.........meet

GOLDIE'S LITTLE SISTER (in homage of Cognito Moto's CB750 - One of my favourite builds and the inspiration to mine)


Image out of Pipeburn





















In the State I live in, if a vehicle is modified significantly like a whole different front end, then it may have to be assessed by an automotive engineer to enable road registration. I'm taking it to my mechanic for initial assessment and he will tell me if that is so. Until I get registration, I can't ride it. In fact my rides around the block were illegal. But she runs!  Keep you posted.
1982 Honda CX500 Roadster build

Offline der_nanno

  • Posts: 529
  • Faster!
    • Greasy Greg
Re: Am I the Pontius Pilate of this CX500?
« Reply #224 on: Aug 04, 2019, 05:40:07 »
I keep on following this. If you use a petrol-filter, don't use the junk with just a mesh as you have the same kind of mesh already inside the fuel tank. Get a decent paper element filter, they are also available as very small ones as installed on Mercedes-Diesels as pre-filters and they come from Mahle in Germany, so it IS decent quality.

You'd be amazed how much dirt comes from a freshly rebuilt tank and or from fuel-pumps at petrol stations.
Real freedom starts with the freedom of thought.

My Blog:
http://greasygreg.blogspot.co.at

My Mule TR1.1 build here on DTT:
http://www.dotheton.com/forum/index.php?topic=75458.0

My Turbo TR1.1 (XV1000) build here on DTT:
http://www.dotheton.com/forum/index.php?topic=72571

My XS Triple Sidecar build here on DTT:
http://www.dotheton.com/forum/index.php?topic=74211

Offline Odontologist

  • Posts: 176
  • Umina Beach, Australia....Where does that part go?
Re: Am I the Pontius Pilate of this CX500?
« Reply #225 on: Aug 04, 2019, 06:25:29 »
No doubt, and thanks der_nanno....but I'm  having trouble finding one on a net search. Can you be more specific? Is it the whole filter or just the paper?
1982 Honda CX500 Roadster build

Offline cxman

  • DTT SUPPORTER
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  • Posts: 2729
Re: Am I the Pontius Pilate of this CX500?
« Reply #226 on: Aug 04, 2019, 08:17:12 »
look for something in the 40-60 max micron range

often small genrators have good ones in that range

onan or kohler come to mind kohler has one that is 20 microns but may restrict wide open fuel flow without a pump

the standard cheapo filter can be in the 60-120 micron range or more and just pass the rust and crap particles right to the clean carbs i see it all the time

something like this will still flow enough fuel but catch crap get 2 carry a spare

https://www.amazon.com/KOHLER-25-050-22-S1-Diameter/dp/B0019MCOD4/ref=asc_df_B0019MCOD4/?tag=hyprod-20&linkCode=df0&hvadid=167120444362&hvpos=1o1&hvnetw=g&hvrand=16431235368214702578&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9009610&hvtargid=pla-314874625132&psc=1
« Last Edit: Aug 04, 2019, 08:23:32 by cxman »
1978 CX650 Super Deluxe
1979 XS1100 Special
1974 xl350
1983 cx650 Custom
1973 cb750
1980 cb750
1981 cb650
1982 cb900 c
1974 kawasaki 350 bighorn
1983 GL1100 aspy full dress
1983 GL1100 Nekid
and a bunch of others

Offline sandmanred

  • Posts: 63
Re: Am I the Pontius Pilate of this CX500?
« Reply #227 on: Aug 04, 2019, 10:53:44 »
Wow, looks great!

Offline crazypj

  • Posts: 13467
  • Split personality, I fake being smart
Re: Am I the Pontius Pilate of this CX500?
« Reply #228 on: Aug 04, 2019, 17:49:09 »
I actually prefer your build to the CB750 inspiration. Mainly, I've never been a fan of CB750 SOHC so something narrower and lighter is always a plus. As for fuel filters, the alloy body ones that unscrew to change filteruse either paper or nylon filters,find out whats available at local 'tuner store for Japanese imports. They were about $10.00 (US)  last time I looked. If they are nylon filter element, you can swap it out for paper cartridge. Oh, the only thing I see wrong for inspection is direction indicators. You may have to fit Australian spec ones then swap back after you have plate on. I used to do MOT's in Britain, you could lose MOT licence for not doing them 'by the book' although things seem pretty slack last few years judging by some of ther bikes from UK posted on DTT
« Last Edit: Aug 04, 2019, 17:53:31 by crazypj »
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline Odontologist

  • Posts: 176
  • Umina Beach, Australia....Where does that part go?
Re: Am I the Pontius Pilate of this CX500?
« Reply #229 on: Aug 04, 2019, 18:18:17 »
Thanks fellas. And thanks for the tips re filters.
Crazypj, my brother told me exactly same thing re indicators and MOT. I'll  take it to my mechanic who is also an inspector of unmodified vehicles so he can give me a list of possible defects.
1982 Honda CX500 Roadster build