RZ/RD 350 & Misc. 2-Stroke Tech BBS

Technical Forums for Two-Stroke Nuts
It is currently Tue Jun 19, 2018 5:32 pm

All times are UTC - 4 hours [ DST ]




Post new topic Reply to topic  [ 9 posts ] 
Author Message
 Post subject: bogs down after idle
PostPosted: Tue May 29, 2018 3:28 am 
Offline
User avatar

Joined: Sat Aug 14, 2010 4:50 pm
Posts: 450
Location: sconsin
With a new engine, I started my bike for a couple of heat cycles and a leak check. The first couple of cycles seemed to go well. The following day, when I started the bike, i believe it sounded good at idle, but as soon as I moved the throttle from idle, and I mean immediately, the engine bogged down instantly and sounded horrible. There was also premix all over the bowls....mostly from what i think were the front top of the bowls. I put a little 32/1 premix in before the initial start up so I could check the oil lines and pump for proper operation. After I noticed the pre-mix on the floats, I took the carbs off and took a look inside, and all seemed good. Then I re-tightened the floats because I thought that was why they were leaking. I then started it up a couple more times. The first couple times it still ran like shit off of idle, but the fuel wasn't there. Now the fuel is back on the carbs and it still runs like crap. I cant figure out why the engine is bogging down after idle.....any suggestions? Could a seep from a float even cause this? Is the fuel coming from somewhere else, but it just seems to be leaking from the floats? Could it be jetting.....electrical? Thank you for any help.


Top
 Profile  
Reply with quote  
 Post subject: Re: bogs down after idle
PostPosted: Tue May 29, 2018 11:19 am 
Offline
-----
-----

Joined: Fri Oct 03, 2003 11:11 pm
Posts: 3369
Location: Southern Ontario, Canada
I don't know about the weeping float bowl gaskets (maybe new gaskets req'd and floats set too high?), but the only time I ever had mine refuse to take any throttle dirty pilot jets were the culprit. I pull a strand of copper from multi strand electrical wire and use that to wiggle around and clean it out without damaging the jet as you would with something harder.


Top
 Profile  
Reply with quote  
 Post subject: Re: bogs down after idle
PostPosted: Tue May 29, 2018 5:07 pm 
Offline
User avatar

Joined: Sat Aug 14, 2010 4:50 pm
Posts: 450
Location: sconsin
The carbs have been cleaned several times....but I will still do as you suggest with the pilot. There are new float gaskets, as well as new gaskets at the top of the carbs. Some of the other things I've tried are listed below.

Pressure tested the engine before installing

Put clear hoses on floats and cracked the float drain screws...level seemed accurate

Ran with the clear hoses on floats to see if petcock was delivering fuel

Im running old Toomey pipes, V-Force 4 reeds, 2/1 Toomey sponge air filter

Started with 25P, Needle 4 clicks down from top on what I think are dynojet needles and 420M, air screw 2 turns out

Switched to 22.5P, Needle 3 clicks from top

Sprayed carb cleaner around intakes and carbs while engine was running and there was no engine reaction

Removed oil lines for now and continue with 32/1 pre-mix

Synced carbs using snail type tester

Ran with gas cap off to make sure breather wasnt the issue

Checked to make sure choke bowl was on the correct carb

Im sure i've done some other things too, but I cant remember what they are. Im gonna switch to 340 mains tonight. Not even sure how I came up with 420 mains, but I think someone told me that was a good set up for Toomey pipes and filter. Not sure if changing mains even makes a difference down at idle anyways, but im out of ideas, money and patience.


Top
 Profile  
Reply with quote  
 Post subject: Re: bogs down after idle
PostPosted: Wed May 30, 2018 9:50 pm 
Offline
User avatar

Joined: Sat Aug 14, 2010 4:50 pm
Posts: 450
Location: sconsin
The pilots were cleaned and inspected... they are good. I checked the float levels again, and I must have been sleeping the first time I checked them! They seem to be very very low. So low, that I feel I didn't do it right this last time. I also noticed that I have 2 different length sets of needle valve needles. Can any size needle valve be used as long as the tang is bent to suit? Anyway, back tonight to try and bend my floats and get my levels within range.


Top
 Profile  
Reply with quote  
 Post subject: Re: bogs down after idle
PostPosted: Thu May 31, 2018 3:36 am 
Offline

Joined: Mon Mar 03, 2014 8:44 pm
Posts: 2729
Location: Alberta, Canada
Raise the clip on the needles to drop them. I think you are way too rich there. It will not hurt anything as long as you go one notch at a time. You may have to do this two or three times.

32:1 is quite rich, in my opinion. 40:1 or even 50:1 would give you less headache. The plug tips will be white if you go too lean.

_________________
Rory


Top
 Profile  
Reply with quote  
 Post subject: Re: bogs down after idle
PostPosted: Thu Jun 07, 2018 6:05 pm 
Offline
User avatar

Joined: Sat Aug 14, 2010 4:50 pm
Posts: 450
Location: sconsin
I feel I have a head gasket leak. There is a lot of "brown" fluid in my pipes, and with the pipes off, and when I turn it over by hand, it looks like fluid is cascading down the cylinder walls from the head.

1. If you do a pressure test, and the engine passes at 7.5 pounds, can you still get a head gasket leak from the higher pressures of a running engine?

2. If you have a head gasket leak, would coolant come into the cylinders, or blow fuel into the coolant system....or both?

3. I have what appears to be a 1/8 ring of rust or something on the top of my cylinder walls. Is this a sign of burning coolant.

4. If the pipes and crankcase are full of this coolant/premix fluid, would that cause the engine to run like shit?

5. Could a bike idle well with a head gasket leak, and go "bwaaa" when you give it throttle?

Im changing the head gasket (a copper one from Wicked) anyway, but I am asking these questions to try and learn from my mistakes......which have been several!! Thanks to all. MAGA.


Top
 Profile  
Reply with quote  
 Post subject: Re: bogs down after idle
PostPosted: Thu Jun 07, 2018 9:06 pm 
Offline

Joined: Tue Nov 12, 2013 2:34 am
Posts: 1035
Juicebox wrote:
I feel I have a head gasket leak. There is a lot of "brown" fluid in my pipes, and with the pipes off, and when I turn it over by hand, it looks like fluid is cascading down the cylinder walls from the head.

1. If you do a pressure test, and the engine passes at 7.5 pounds, can you still get a head gasket leak from the higher pressures of a running engine? Head gasket can insta-leak once the coolant gets hot. I don't know why but it happens. When running you would likely see bubbles if you start it with the coolant cap off or at least this happened on one of mine with a bad head gasket. Combustion gasses were getting in coolant system

2. If you have a head gasket leak, would coolant come into the cylinders, or blow fuel into the coolant system....or both? Yes, both.

3. I have what appears to be a 1/8 ring of rust or something on the top of my cylinder walls. Is this a sign of burning coolant. How long did it sit? Rust would be indicative of some water based fluid. Does not mean re-bore needed.

4. If the pipes and crankcase are full of this coolant/premix fluid, would that cause the engine to run like shit? Coolant is unlikely to get into the crankcase. Not sure about rest. If you have water in the combustion chamber, combustion will be poor

5. Could a bike idle well with a head gasket leak, and go "bwaaa" when you give it throttle?

Im changing the head gasket (a copper one from Wicked) anyway, but I am asking these questions to try and learn from my mistakes......which have been several!! Thanks to all. MAGA.


New factory head gasket likely just as good an option. Head gaskets mysteriously fail on new start with these bikes.

It sounds like you have gone through the carbs fairly well. If you have a head gasket leak, fix it first then move on to see if other problems.

Hopefully this helps. I had a similar issue with a gasket leak after a fresh rebuild. I had air bubbles in the coolant when running with the cap off the therm which was the giveaway. No fluid in exhaust so mine must have been minor.


Top
 Profile  
Reply with quote  
 Post subject: Re: bogs down after idle
PostPosted: Tue Jun 12, 2018 3:48 am 
Offline
User avatar

Joined: Sat Aug 14, 2010 4:50 pm
Posts: 450
Location: sconsin
Thanks for the answers sir. As for the rusty colored rings, this is a brand new build and was beautiful when assembled. These rings appeared in about a week after only running it to make checks on the engine. I wont get into why, but the engine I took out of the bike was a fresh build also and has about 50 miles on it. That engine also has rust colored rings at the top of the cylinders. Now my new engine has these rings too....im baffled. Anyone in Wisconsin wanna make a friend and help me get this thing running properly?


Top
 Profile  
Reply with quote  
 Post subject: Re: bogs down after idle
PostPosted: Tue Jun 12, 2018 7:49 am 
Offline

Joined: Thu Sep 15, 2011 9:06 pm
Posts: 176
Location: Chicago Il.
I dont think those are rust rings. I think it is a ring of burnt oil from combustion. That is where the ring stops when piston is at its highest. I think it is normal. I think it sounds like carbs to me or if your powervalves are stuck in a odd position or are adjusted way off. What area of wisconcin do you live in?

_________________
1984 Rz350, Wicked Toomey rep pipes, Dynojet kit,Zeel unit,Toomey Y boot filter.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC - 4 hours [ DST ]


Who is online

Users browsing this forum: 2bang and 4 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group