73 Cl175 K7 will not idle

DTW350

New Member
I have a 73 CL175 K7 that will not idle. Here is what I have already addressed: points timing is spot on, all potential vacuum leak areas have been sealed on the carbs, carbs have been synced, idle circuits on both carbs are clean with compressed air three times, slides are completely bottomed out at idle stage, choke mechanism works as it should, jets are stock and needles, floats are set at stock 21mm. I can start the bike by opening the throttle up but I have to hold the throttle above 2k rpm, anything below this will kill the bike, it will not run without holding the throttle open. I have great spark, all mechanism are in good working order. Somebody suggested I disconnect the throttle cables completely in case the slides are not bottoming out, tried that, bike will not start at all in this condition. Absolutely aggravating. Any ideas, thoughts here? Thanks in advance!
 
I am not doubting that you think the carbs are clean, but the symptoms do suggest blocked idle circuits.

On those carbs there are tiny pilot jet outlets at the front edge of the slide. It is very common for those to block. Please re-check those outlets - they are tiny (less than 1mm) in diameter.
 
How do you suggest I clear those holes out? I did spray carb cleaner through the pilot jet end and I saw it spray out through those holes. I assumed that would do the trick, I guess it needs further investigation.
 
What I do is to strip both crabs and spray through every drilling. Do one drilling in one carb and then compare that to the same drilling in the other carb. Flow should be similar.

Have another look at those outlets and then check the jets - air holes and fuel hole and then go back through the air circuits as well. If there's no airflow, there is usually no fuel flow either.
 
Other ideas to consider would be timing chain tension. As well, I am not sure how the flywheel is connected to the crank on that bike, but if it uses a half moon or straight type of pin, it could be partially sheared, this will put the timing off hence the racing engine. JMO.
 
Thanks for the replies. Interestingly today I decided to do a compression test. I am getting 45PSI on each side! This is crazy low. Is it even possible for a bike to run at this low of compression? As I said before, I can get it to run but it does die below 2k roms. The tester I am using is a Harbor Freight brand, so it could just be the tester. I am ipening the choke, bith plugs out and full throttle, kill switch off. Is there something I am not seeing here...besides compression? 8)
 
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