Technical Discussion Topics related to Technical Issues

Motor swap mystery

Old 08-16-2011, 08:22 PM
  #1  
Senior Member
MotoGP
Thread Starter
 
smokinjoe73's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 4,910
smokinjoe73 is on a distinguished road
Motor swap mystery

OK so thanks for fielding all my wacky questions, BUT

The swap is done (98 motor out, 05 motor in). I fired it up today and it showed the EXACT SAME PROBLEMS AS THE OLD MOTOR!!!!!!!.

Only runs on choke, white smoke out the rear cylinder, etc. No way could both motors have the same issues, so I must look elsewhere. Maybe a carb float is stuck? I dont recall seeing this before but its weird.

If anyone has seen or heard anything like it let me know. I havent looke much but both spark plugs are firing visually strongly.
smokinjoe73 is offline  
Old 08-16-2011, 08:30 PM
  #2  
Senior Member
SuperSport
 
jay956's Avatar
 
Join Date: Aug 2009
Location: Richmond, VA
Posts: 684
jay956 is on a distinguished road
are you using the same carbs?
jay956 is offline  
Old 08-16-2011, 08:50 PM
  #3  
Senior Member
Back Marker
 
Join Date: Apr 2011
Posts: 201
msethhunter is on a distinguished road
Could be that the rear carb is dumping too much fuel into the rear cyl. I have seen excessive fuel cause white smoke in cars(stuck injector). If you have the old motor still, I'd pull the head off and see if you find anything obvious. Look for signs that the fire ring of the head gasket was compromised. Sounds to me like you have a candidate for a bitchen engine build now, as in a good usable core.

How does it run? It could also be that the carb has a crack in one of the cooling passages, and is allowing coolant in that way. Get some needle nose vice grips if you have them, or regular ones if you don't, and pinch off the coolant hose to the carb. DON'T GO TO TIGHT! If you do, you could damage the hose. You want just enough to stop the flow of coolant to the carbs.
msethhunter is offline  
Old 08-16-2011, 09:59 PM
  #4  
Senior Member
MotoGP
Thread Starter
 
smokinjoe73's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 4,910
smokinjoe73 is on a distinguished road
That sounds reasonable. For years I had the coolant lines to the carbs clamped to prevent flow. Recently I unclamped one ( the rear I think). This has been frustating since racing keeps taking me out of town so days go by that I cant dig into it.

Oh yeah, same carbs, same everything, new motor.
smokinjoe73 is offline  
Old 08-17-2011, 05:26 AM
  #5  
Senior Member
Back Marker
 
motormouth's Avatar
 
Join Date: Mar 2010
Location: Scottsdale , AZ
Posts: 233
motormouth is an unknown quantity at this point
Probably be a good idea to test new engine leakdown and compression. Probably a good time to check / adjust valves. Then tinker with carbs. Just my 2 sense.
motormouth is offline  
Old 08-17-2011, 08:35 AM
  #6  
Senior Member
Back Marker
 
Join Date: Apr 2011
Posts: 201
msethhunter is on a distinguished road
Originally Posted by motormouth View Post
Probably be a good idea to test new engine leakdown and compression. Probably a good time to check / adjust valves. Then tinker with carbs. Just my 2 sense.

That a good idea, once he gets it running better. If he can't get it warmed up necause it puking smoke, the compression and leak down tests will not be accurate. Those are supposed to be done on an engine at operating temp.
msethhunter is offline  
Old 08-17-2011, 08:42 AM
  #7  
Senior Member
SuperSport
 
jay956's Avatar
 
Join Date: Aug 2009
Location: Richmond, VA
Posts: 684
jay956 is on a distinguished road
my thinking could be too simple but.... seems to me if everything changed except the carbs, and the problem persists.... then its gotta be the carbs.
jay956 is offline  
Old 08-17-2011, 09:03 AM
  #8  
Senior Member
SuperBike
 
RCVTR's Avatar
 
Join Date: Dec 2005
Location: South Lake Tahoe, CA, USA
Posts: 1,689
RCVTR is an unknown quantity at this point
If it's fuel, the plug and piston should be covered in black soot.

If it's coolant they will be way too clean.
RCVTR is offline  
Old 08-17-2011, 09:03 AM
  #9  
Senior Member
SuperSport
 
thetophatflash's Avatar
 
Join Date: Jan 2005
Location: Nooksack WA
Posts: 830
thetophatflash
Same fuel?
thetophatflash is offline  
Old 08-17-2011, 09:34 AM
  #10  
Senior Member
Back Marker
 
Join Date: Apr 2011
Posts: 201
msethhunter is on a distinguished road
Originally Posted by RCVTR View Post
If it's fuel, the plug and piston should be covered in black soot.

If it's coolant they will be way too clean.

Depends on how much fuel. Remember, fuel is a solvent. So if it's putting so much fuel in the cyl. that it's blowing white smoke, the cyl. will look the same as a coolant steamed cyl. I had to find that one out the hard way. I was a young auto tech, and did a cyl head gasket under warranty because a car was belching white smoke and was down a cylinder. Pulled the head off without a proper diagnosis and couldn't find anything obvious(I was frustrated because of what car it was, and assumed it was a head gasket because of how much a bitch it was going to be). Replaced the head gasket and the problem was still there. So I did a proper diagnosis and found out that one of the injectors was stuck open. Luckily it was under warranty, so the repair was covered. Had it been on the customer for the repair, I would have done a cylinder head gasket on a PT Cruiser Turbo for free. Not exactly the easiest car to do a head gasket one.
msethhunter is offline  
Old 08-17-2011, 09:36 AM
  #11  
Senior Member
Back Marker
 
Join Date: Apr 2011
Posts: 201
msethhunter is on a distinguished road
Originally Posted by jay956 View Post
my thinking could be too simple but.... seems to me if everything changed except the carbs, and the problem persists.... then its gotta be the carbs.

+1. New engine, same problem. I highly doubt that the new engine has the exact same problem. Block off the coolant passages, rinse, repeat.
msethhunter is offline  
Old 08-17-2011, 09:38 AM
  #12  
Senior Member
Back Marker
 
Join Date: Apr 2011
Posts: 201
msethhunter is on a distinguished road
Originally Posted by thetophatflash View Post
Same fuel?

I see your point, and it's definatly valid, if it was both cylinders. But, it's only 1 cylinder, so I doubt it's the fuel.
msethhunter is offline  
Old 08-17-2011, 09:56 AM
  #13  
Senior Member
SuperBike
 
scottiemann's Avatar
 
Join Date: Feb 2007
Location: boston
Posts: 1,252
scottiemann is on a distinguished road
I had an issue with my SH running like [email protected]# after sitting for a while... it ran like as$ and at the same time acting as if it was running out of gas and getting too much gas..

turned out to be the float pin was sticking and I was able to free it up and scrape off the crap and put it back together...

ran fine after that, dont know if this helps but it was my experience
scottiemann is offline  
Old 08-17-2011, 05:55 PM
  #14  
Senior Member
Superstock
 
bass4dude's Avatar
 
Join Date: Jan 2011
Location: Santa Clara, CA
Posts: 258
bass4dude is on a distinguished road
If it will only run on choke that is saying something about the running conditions of the bike/jetting.

If it was previously running properly and NO jetting changes were made, you may have a clogged main jet or emulsion tube. If it is not one of those then you should flush out the fuel inlets and see where the fuel is coming out. I would recommend pulling the slides out as the diaphragms are somewhat fragile.

If one of your chokes nuts is cracked and the plunger is not closing the enrichment circuit all the way, that may be why it isn't running properly as well. Mine is broken off completely and I have to run on almost full choke because the difference between the cylinders is enough to change whether it will run or not. If it's not cracked, double check to make sure that the seal on the end of the brass plunger is okay as well because that could be broken as well.

For other "duh" moments, check carb boots for leaks, double check plugs and coils. Not likely the problem, but once you've removed all other options, what's left is the solution

and just as a question that could help you later on down the line, do you have another bike with a fuel pump that you could use to pressure test your carbs?
bass4dude is offline  
Old 08-17-2011, 09:45 PM
  #15  
Senior Member
SuperSport
 
geekonamotorcycle's Avatar
 
Join Date: Jan 2011
Location: Tampa Florida
Posts: 521
geekonamotorcycle is on a distinguished road
geekonamotorcycle is offline  
Old 08-22-2011, 06:53 PM
  #16  
Senior Member
MotoGP
Thread Starter
 
smokinjoe73's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 4,910
smokinjoe73 is on a distinguished road
Yes geek it resembled that condition alot except mine runs at idle but dies at throttle input. I disassembled and cleaned the carbs to get to this point. BTW you didnt have to dismantle the throttle at the grip, just remove the 2 small screws holding the cables onto the carbs.
smokinjoe73 is offline  
Old 08-22-2011, 07:13 PM
  #17  
the boss
SuperBike
 
saige's Avatar
 
Join Date: Mar 2010
Location: largo,fl
Posts: 1,182
saige is on a distinguished road
im wondering,and this is for giggles,but,is it possible that maybe the petcock is failed and the diaphragm is split just a little where there is fuel returning to the head thru the vacuum port.
geek had that same problem,but his was more entertaining lol.his was 1 in a million.dont know how it was running.
but that could cause smoke and to run crappy.just a thought.
saige is offline  
Old 08-22-2011, 07:29 PM
  #18  
Senior Member
SuperSport
 
geekonamotorcycle's Avatar
 
Join Date: Jan 2011
Location: Tampa Florida
Posts: 521
geekonamotorcycle is on a distinguished road
Yah on my bike my petcock was not engaging because it was loose. So they might be similar problems. Even if your choke is working I am willing to bet you have a fuel issue.
geekonamotorcycle is offline  
Old 08-22-2011, 07:55 PM
  #19  
Senior Member
MotoGP
Thread Starter
 
smokinjoe73's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 4,910
smokinjoe73 is on a distinguished road
Yes, a fuel issue, did you replace or repair the petcock? I have the same smoke as on one of your videos. Saige, what was the resolution?
smokinjoe73 is offline  
Old 08-22-2011, 08:30 PM
  #20  
Senior Member
MotoGP
 
7moore7's Avatar
 
Join Date: Jul 2010
Location: Phoenix, AZ
Posts: 3,867
7moore7 is on a distinguished road
I had bad luck with a rebuild kit. This OEM part number has all the gaskets and such that can go bad, save one spring (which really can't go bad):

16953-ML0-034

I used it and it solved some petcock issues that I had...
7moore7 is offline  
Old 08-22-2011, 08:55 PM
  #21  
the boss
SuperBike
 
saige's Avatar
 
Join Date: Mar 2010
Location: largo,fl
Posts: 1,182
saige is on a distinguished road
Originally Posted by smokinjoe73 View Post
Yes, a fuel issue, did you replace or repair the petcock? I have the same smoke as on one of your videos. Saige, what was the resolution?
we didnt want to wait for a rebuild kit,i had a extra petcock and gasket,so i went over and help him change it and problem gone,luckily the petcock was a good one.
geeks had a minute tear in the diaphragm and that caused a leak,but like i said,his was one in a million,the vacuum was on the wrong nipple (geek,for the love of god,try not to laugh) and it still ran for months and months.so once it was changed,no fuel was going into the head anymore and it ran stronger than before.
i would say,try to source a good petcock or get a full good rebuild kit,its a cheap start.hopefully,that is the problem or will lead you to it.
one question,is smoke coming out of both cans or just one.if just one,it should be your left can.
saige is offline  
Old 08-22-2011, 09:57 PM
  #22  
Senior Member
MotoGP
Thread Starter
 
smokinjoe73's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 4,910
smokinjoe73 is on a distinguished road
OK but when I apply vacuum to the petcock it gushes fuel out the 2 feeds, no leaks so I dont think I have that issue, right?
smokinjoe73 is offline  
Old 08-22-2011, 10:10 PM
  #23  
Senior Member
MotoGP
 
7moore7's Avatar
 
Join Date: Jul 2010
Location: Phoenix, AZ
Posts: 3,867
7moore7 is on a distinguished road
Nah it doesn't sound like it. FWIW mine still functioned when it wasn't working correctly (as in gushed out both sides). But other than that my symptoms were all completely different from yours. And it sounds like Geek was sucking fuel into his rear cylinder through the vacuum line, which is a one in a million shot!

I'm kinda curious about the smoking exhaust now... is it coming out of both pipes?

Are your carb slides seated correctly? If you pull them back, do they return kinda slowly or snap back quickly? They should return slowly...
7moore7 is offline  
Old 08-22-2011, 10:27 PM
  #24  
Senior Member
MotoGP
Thread Starter
 
smokinjoe73's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 4,910
smokinjoe73 is on a distinguished road
I cleaned and reassembled the carbs and they both seem to slowly slide shut so I think the diaphragms are sealing. Cant open the throttle still tho
smokinjoe73 is offline  
Old 08-23-2011, 10:04 AM
  #25  
the boss
SuperBike
 
saige's Avatar
 
Join Date: Mar 2010
Location: largo,fl
Posts: 1,182
saige is on a distinguished road
The gas was coming back thru the vacuum into the head,but some gas came out the mid pipe.
My guess is choke related or maybe something fell in and is clogging the throttle body.
saige is offline  
Old 08-23-2011, 11:21 AM
  #26  
Member
Squid
 
Join Date: Apr 2011
Location: YUMA AZ
Posts: 44
FLETCH is on a distinguished road
Do you have oil in the airbox? Sometimes high oil level or excessive crankcase pressure can force oil into air box. Seen excessive blow by cause the pressure or even a carb leaking fuel into cylinder then leaking past rings causing higher oil level and excess pressure. Carb coolant leak as mentioned above sounds plausable as well.
FLETCH is offline  
Old 08-23-2011, 10:04 PM
  #27  
Senior Member
MotoGP
Thread Starter
 
smokinjoe73's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 4,910
smokinjoe73 is on a distinguished road
OK guys. I am including this only to save others the same fate. It was all due to bad gas, maybe a tankful of diesel somewhere near Binghampton on my trip home.

That is why the new motor acted the same. I finally broke down & swapped the tank from my other vtr and it is running better. Now I have an '05 motor in my '98 and a ton of mechanic training. I drained the offending fuel and should be on the road tomorrow.
smokinjoe73 is offline  
Old 08-23-2011, 10:15 PM
  #28  
Senior Member
SuperBike
 
killer5280's Avatar
 
Join Date: Aug 2004
Location: Atlanta, GA
Posts: 1,728
killer5280 is on a distinguished road
Originally Posted by smokinjoe73 View Post
OK guys. I am including this only to save others the same fate. It was all due to bad gas, maybe a tankful of diesel somewhere near Binghampton on my trip home.

That is why the new motor acted the same. I finally broke down & swapped the tank from my other vtr and it is running better. Now I have an '05 motor in my '98 and a ton of mechanic training. I drained the offending fuel and should be on the road tomorrow.

I would never have admitted this in a million years.
killer5280 is offline  
Old 08-23-2011, 10:21 PM
  #29  
Senior Member
MotoGP
Thread Starter
 
smokinjoe73's Avatar
 
Join Date: Jul 2007
Location: NYC
Posts: 4,910
smokinjoe73 is on a distinguished road
No but I always ask crashers/ stolen bike stories to tell what really happened. I am no hypocrate. This is what happens when a motor swap becomes easier than digging around.
smokinjoe73 is offline  
Old 08-23-2011, 10:29 PM
  #30  
Senior Member
SuperBike
 
killer5280's Avatar
 
Join Date: Aug 2004
Location: Atlanta, GA
Posts: 1,728
killer5280 is on a distinguished road
Originally Posted by smokinjoe73 View Post
No but I always ask crashers/ stolen bike stories to tell what really happened. I am no hypocrate. This is what happens when a motor swap becomes easier than digging around.
If you say so.

Glad you found the problem.
killer5280 is offline  

Thread Tools
Search this Thread
Quick Reply: Motor swap mystery


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.

All times are GMT -7. The time now is 04:00 AM.


© 2019 MH Sub I, LLC dba Internet Brands