1979 PE 175

[notsoaverageguy]

I have a 1979 PE 175 thats not running right, heres the history. It was my buddies bike sitting inside a storage container for at least 15 years. No sun no wind no rain. I brought it home and of course took off the carb and cleaned it in my drop tank. It cleaned up fine. Checked the float level (live) and its stock. I then cleaned the tank and petcock and wanted to ride it and see where I stood. Rode it for 30 mins just fine torquing around up and down hills. I never needed to get on the pipe. But when coming home I decided to see how well it did run. It wont get on the pipe! As soon as the revs pick up it acts like its dying and when you let off the gas it comes right back to running just fine.This bike is bone stock, never had a re-bore pipe or even after market silencer installed. So I naturally thought clogged air filter. Opened it up and the dirty discussting thing just fell apart in my hands. Great solved that one! Except it didnt???? Brand new air filter changed nothing.Hmmm how could anything get in that pipe? I dont know but I will pull it and check it. Yup nothing did get in there. Must have messed up the carb somehow. Took it back off, nope. Recheck the petcock ...nope??? Pull the plug.its fine. I am stumped. It will sit and idle all day long, run around the hills all day long (off the pipe) but wont transition. I did after jerking it around on and off get it to hit the pipe, but it wont stay more than a few seconds. Obviously not an ignition side crank seal as it will idle all day. Clutch side seal??? It doesnt blow smoke. I am stumped. One other weird thing. If you try to start it up with the choke, it will start rev somewhat high (I would say normal for the choke being on) and die. EVERYTIME. 10-20 times. You then take the choke off and it starts and idles all day. So there it is??? What do you think?

[1976RD400C]

Sounds like it doesn't have a good fuel flow/supply. Disconnect the hose from the carb, hold a can there, and open the petcock. Does it flow strong and continue to flow. If all is good there I would suspect the main jet is somewhat plugged.

[scully]

Does it now have an air filter in it ? Did you remove the needle jet to clean it and the air jet passage to the needle jet. Air filter may have plugged the air jet when it disintegrated. 

[notsoaverageguy]

It has perfect fuel flow. As I stated I completely disassembled the carb and soaked it in a chemical tank. It is not the carburetor including main jet jet needle, float level, needle jet or vent. And as stated it has a brand new Uni air filter. I get that's what it sounds like as you can read from my post and what I have done. The screen in the petcock is perfectly clean. When off the tank you can open the valve and see straight through it. It does not have a bowl or vacuum driven mechanism. It's a straight on/off valve.

[Djg8493]

New fuel lines?  Believe it or not I have had an old black fuel line begin to breakdown inside and disrupt fuel flow.  It even had small pieces break off and get stuck in the carb inlet. 

[SoCal250]

When you disassmbled and dipped the carb and parts did you blow air through all the passages and make sure the jets were completely clean? Dipping alone does little to clean the internals.

[paul1478]

When you disassmbled and dipped the carb and parts did you blow air through all the passages and make sure the jets were completely clean? Dipping alone does little to clean the internals.

Yes exactly. I have seen countless running issues on the FJ thread were people say this exact thing. A very small pc of crud will make you chase an issue that may still be in the carbs. Happened to me when I first got my FJ.

[m in sc]

check fuel tank vent and petcock as well.

[teazer]

Sounds like an issue with the "ECU"  PEI uses a proprietary timing arrangement in the ECU.  I believe that replacement CDI boxes may be available to get someone top test the system on a test jig and have them run it up to top engine revs to plot the timing curve and see if it's OK.

Rex's Speed Shop in the UK can probably test it and tell you if it's OK.

[notsoaverageguy]

So nobody thinks a possible clutch side crank seal? Well thats reassuring. Obviously I dont want to tear into the engine. And it just doesnt sound like it would cause a loss of power, maybe smoke but cant see it really being part of the problem. And I know what it sounds like its just that I have had the carb off twice now since this problem (and of course I blew out the passages after dunking the carb). FYI I was a motorcycle and car mechanic most of my life. And not to be an ass but its frustrating when I do run into a stumper because in my circle of friends I dont know anybody more experienced to run a problem like this by. Thats why I do love the internet as there is a wealth of guys smarter than me, to help out. But since that is exactly what it seems to still be I will pull the carb again, and give another full disassembly looking specifically at the secondary circuit and needle and seat. I will definitely post what I find.

[Cdffiredad]

I know this sounds a bit odd but try testing it with the muffler off.

[pdxjim]

I know this sounds a bit odd but try testing it with the muffler off.

I second this.

I had a KE175 BITD that showed the same symptoms til I reamed out the baffles in the "expansion chamber" with a long ship auger drill.

[notsoaverageguy]

Hadnt got to it yet, but I already took off the exhaust blew compressed air through the pipe and tried it without the muffler.

[jradnich]

Sounds like an issue with the "ECU"  PEI uses a proprietary timing arrangement in the ECU.  I believe that replacement CDI boxes may be available to get someone top test the system on a test jig and have them run it up to top engine revs to plot the timing curve and see if it's OK.

Rex's Speed Shop in the UK can probably test it and tell you if it's OK.

Teazer may be onto something. Is your problem RPM or throttle related?