04-18-2023, 02:20 PM
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#1 |
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Join Date: Oct 2016
Location: Carrollton, GA
Posts: 1,467
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LOTS of blowby on the Hawk
So it's a beautiful day here in West Georgia, and once I got the yard work done for the day, I decided to take the Hawk out to go get my hair cut. It was slightly low on oil when I left, but it's a short ride and I wanted to get the oil hot and check it again. This is also only the second time I've ridden the Hawk this season. When I got back to the house, I checked the oil again and it was indeed low. So I decided to open the filler cap with the engine running, and the crankcase pressure nearly blew the cap off in my fingers. There was a pretty good bit of blowby coming out. This is confusing for me because A) the bike doesn't have very many miles on it (3,375 to be exact) and B) the bike is pretty well taken care of. It's not like it was laying on it's side in a field all winter. It was in the shop enjoying the sheltered life. The bike runs fantastically well, no issues there, and it has plenty of power. Is anyone else seeing huge issues with blowby? Would adding a little Marvel Mystery Oil to the crankcase before the next ride be a good idea?
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First Rule of Aviation: -Never Pass Up The Opportunity to Pee I was struggling to get my wife's attention; I sat down on the couch and looked comfortable. That did the trick! My wife says I only have two faults. I don't listen and something else... If at first you don't succeed, try doing it the way I told you to... The Stable: 2005 Yamaha V-Star 650 - SOLD 2015 Suzuki DR 650 2015 RPS Hawk 250 - SOLD 2016 Ural Gear Up |
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04-18-2023, 02:56 PM
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#2 |
Join Date: Apr 2023
Location: Near Saginaw Mich.
Posts: 180
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Sounds like the normal crankcase pressure from a running engine and nothing to be concerned about as long the the engine runs fine.The normal motion of the piston going up and down creates pressure that usually stays inside the engine. Until you opened the filler cap and let it out.
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04-18-2023, 09:34 PM
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#5 | ||
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Join Date: Oct 2016
Location: Carrollton, GA
Posts: 1,467
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Quote:
Quote:
Bruces, The vent tube goes right into the intake elbow behind the pod filter I put on. No kinks or obstructions. I'll probably take it off tomorrow when I do the compression test and see if I'm oiling up the inside of my carburetor. If I'm getting loads of oil through the carb, I'll know for sure that something is off. If not, I'll take it out for a good long ride and see what I get after that. Thanks to everyone for the advice!
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First Rule of Aviation: -Never Pass Up The Opportunity to Pee I was struggling to get my wife's attention; I sat down on the couch and looked comfortable. That did the trick! My wife says I only have two faults. I don't listen and something else... If at first you don't succeed, try doing it the way I told you to... The Stable: 2005 Yamaha V-Star 650 - SOLD 2015 Suzuki DR 650 2015 RPS Hawk 250 - SOLD 2016 Ural Gear Up |
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04-29-2023, 04:10 PM
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#6 |
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Join Date: Oct 2016
Location: Carrollton, GA
Posts: 1,467
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A little slow to get on this...
Ok, so after a few really long days that felt like weeks, I finally had some time to do the compression test on the Hawk.
I took three tests: 1) Engine cold, WOT - 145psi https://www.chinariders.net/attachme...1&d=1682798972 2) Engine cold, a couple squirts of oil in the cylinder, WOT - 150psi https://www.chinariders.net/attachme...1&d=1682798972 3) Engine warmed up (about 10 minutes, quick ride around the yard), WOT - 175psi. https://www.chinariders.net/attachme...1&d=1682798972 I'm pretty sure these numbers are perfectly acceptable, and there wasn't any leakdown on the gauge. Still not sure what would cause so much blowby.
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First Rule of Aviation: -Never Pass Up The Opportunity to Pee I was struggling to get my wife's attention; I sat down on the couch and looked comfortable. That did the trick! My wife says I only have two faults. I don't listen and something else... If at first you don't succeed, try doing it the way I told you to... The Stable: 2005 Yamaha V-Star 650 - SOLD 2015 Suzuki DR 650 2015 RPS Hawk 250 - SOLD 2016 Ural Gear Up |
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04-29-2023, 06:09 PM
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#7 |
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Join Date: Dec 2020
Location: Dayton Pa.
Posts: 941
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Well thats great,don't know what to think. Whats the fuel like, I only run high test gas in mine. Are you running stock air filter? oh i see your running a pod air filter. I would go back to stock, honda xr 125 filter is on mine. Still thinking what would cause so much blow by, Whats your valves look like. Maybe be too tight. Or a bad head gasket. Hope this helps.
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04-29-2023, 06:56 PM
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#8 |
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Join Date: Oct 2016
Location: Carrollton, GA
Posts: 1,467
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Buzz, a bad head gasket or valves not set right would show up as leakdown during the compression test. I didn't have any movement on my gauge after 15 or 20 seconds... I'm running premium (91 Octane, in my area) gas treated with Sta-bil and Marvel Mystery Oil. The valves are set correctly (a little on the loose side, even), and the plug looks fantastic. I forgot to add this picture in with the other three.
https://www.chinariders.net/attachme...1&d=1682808800 Honestly, I think I'm just going to send it and hope for the best. It's coming up on time for an oil change anyway, so I may just put some Marvel in the crankcase oil a couple miles before I do the oil change. The side cover will also need to come off so I can clean the slinger, so I'll have a really good opportunity to see what's going on inside.
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First Rule of Aviation: -Never Pass Up The Opportunity to Pee I was struggling to get my wife's attention; I sat down on the couch and looked comfortable. That did the trick! My wife says I only have two faults. I don't listen and something else... If at first you don't succeed, try doing it the way I told you to... The Stable: 2005 Yamaha V-Star 650 - SOLD 2015 Suzuki DR 650 2015 RPS Hawk 250 - SOLD 2016 Ural Gear Up |
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04-30-2023, 12:52 PM
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#9 |
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Join Date: Jan 2021
Location: Lehigh Valley Area
Posts: 164
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Looking at doing a compression test on my bike, TBR7, what is an acceptable pressure?
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- My 3 Bikes: 1. TaoTao TBR7 (My TBR7 Upgrades) 2. Boom Vader (FYI: My Boom Vader Upgrades) 3. 1978 Suzuki SG750 --------------------------------------------- Testing a YouTube Channel 
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04-30-2023, 05:41 PM
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#10 |
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Join Date: Jul 2022
Posts: 94
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If you had low oil it could be hotter than normal causing Blow by. I left my oil cap off the valve cover on my van and 1/2 quart of oil blew out. Also condensation from sitting will steam off. I have also been told putting MM oil in a 2 stroke is good but in a 4 stroke it is not needed. I always used it but noticed the intake and MAP sensor became very greasy. Was afraid it would clog my Cat on my van. I don't think it will hurt your bike though.
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05-01-2023, 05:29 PM
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#11 |
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Join Date: Oct 2016
Location: Carrollton, GA
Posts: 1,467
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Clash, I'm only planning on running the Marvel for a few hundred miles. Really, just enough to break up any carbon or stickiness from the system. It's a fantastic cleaner, but I've heard that it doesn't play super nice with wet clutches.
CheapThrills, anything over about 140 is good. An engine will run with pressures as low as 90-100 pounds. Another good indicator is how long it takes to build pressure. If pressure builds quickly with only a few revolutions, you're in good shape. If it take a long time, that could indicate bad valve adjustment or leaking piston rings. Also, don't forget to hold the throttle wide open when you're doing the test.
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First Rule of Aviation: -Never Pass Up The Opportunity to Pee I was struggling to get my wife's attention; I sat down on the couch and looked comfortable. That did the trick! My wife says I only have two faults. I don't listen and something else... If at first you don't succeed, try doing it the way I told you to... The Stable: 2005 Yamaha V-Star 650 - SOLD 2015 Suzuki DR 650 2015 RPS Hawk 250 - SOLD 2016 Ural Gear Up |
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05-01-2023, 09:28 PM
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#12 |
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Join Date: Dec 2020
Location: Dayton Pa.
Posts: 941
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By bad head gasket I mean it will suck oil from hole where push rods are.No compression leak.See it a lot on Briggs& Stratton small engines,but that smoke is coming out exhaust pipe. Just a thought, as long as it runs good ride it till it get worst.Good compression, how many miles?
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05-02-2023, 05:43 AM
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#13 |
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Join Date: Oct 2016
Location: Carrollton, GA
Posts: 1,467
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Buzz, everything seems fine apart from that bit of blow-by. And after thinking about it for a few days, it could just be that there was a bit of condensate moisture in the crankcase that was just getting hot enough to vaporize off. That was the first time this season that I really cranked it up and rode it around a bit. I'll keep an eye on it, but overall I think I'm just going to leave well enough alone. As for the mileage, I've got about 3,500 miles on the clock, if I remember correctly. I'll double check when I head out to the garage later today.
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First Rule of Aviation: -Never Pass Up The Opportunity to Pee I was struggling to get my wife's attention; I sat down on the couch and looked comfortable. That did the trick! My wife says I only have two faults. I don't listen and something else... If at first you don't succeed, try doing it the way I told you to... The Stable: 2005 Yamaha V-Star 650 - SOLD 2015 Suzuki DR 650 2015 RPS Hawk 250 - SOLD 2016 Ural Gear Up |
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05-02-2023, 12:08 PM
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#14 |
Join Date: Mar 2010
Location: Volcano, Ca
Posts: 7,112
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Sounds normal to me. if you hook up a plastic garbage bag to your crank vent, it will blow it up rather quickly.
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"Light a fire for a man, and you heat him for a day. Light a man on fire, and you heat him for the rest of his life." 2007 Suzuki DRZ400S (SM convert) 2009 Q Link XP 200 1967 BSA B25 250cc Starfire 2022 Royal Enfield Interceptor 650 2023 Royal Enfield Scram 411 1948 Royal Enfield Model G 350 |
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05-02-2023, 09:34 PM
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#15 |
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Join Date: Dec 2020
Location: Dayton Pa.
Posts: 941
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Emerikol think you right,and thats not too many miles. I thought you had a lot of blow by,just trying to help. Sounds like you are ok,have fun and be safe. Keep an eye on your oil,seen other ones run low on oil.And that was it,check mine every week.
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