SRX engine compression

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blueice2001

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Oct 3, 2011
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Rockford, Illinois
I have a 2000 SRX that I just bought used. It has 18000 miles on it but has been taken very good care of. The problem I have is when cold, it is very hard starting. Just a little shot of starting fluid it fires right up. The compression accross all three cylinders was 110. Local Yamaha dealer told me starting issue was due to compression being low so I order new rings and everything to seal it up. After installing rings and running about 5 minutes, while filling and bleeding cooling system I shut engine off and did another compression check, to find same 110 lbs in all cylinders. Also no change in starting, still hard. Does it take more time for rings to seat fully? I am not to famillar with 2 strokes. Any input greatly appreciated.
 

Is the choke setting proper[there is 2 settings for full on and halfway]?Is it hard to pull over or does not take mutch of a pull?It could be the stater gone weak if the carbs and settings are proper.Borrow another gage but it dosent sound like compression problem as it will start fine if all 3 are the same.





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Try a couple different guages before you get too caught up in the 110 number...the fact that all cylinders are reading about the same makes me suspect the guage accuracy. Some of these SRXs are hard starters..try doing a search and you will find all kinds of info and possible fixes.
 
how old is the fuel :ban: . my sled was very hard to start this summer , i put in fresh fuel one loop around the yard in the grass . starts normal now
 
New fuel and two different compression testers used. Engine sounds fine after I get it fired. Idles fine and seems responsive when I rev it up with track raised. If stator was weak would it start fine after I get it started? Oh yeah, it pulls over like it has a ton of compression. after 5-6 pulls, I am wore out(lol).
 
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I know with high altitude comp numbers are lower but in illinois I doubt thats the issue. I agree with something is hankey with gauges or process in doing test. For those numbers to be correctthe bore of hte jugs would need to be WHOOPED and new rings would have cchanged it at least a little bit. Hard to beleive it could be base or head gasket issue on all 3. Hard starting I would say bad fuel, weak stator or could be a choke issue, check that full choke is fully pulling choke. When I picked up the last sxr the choke was backed out to the point that full choke only pulled to warming position.
 
Another trick I have heard of but never tried is when you pull the plug to hook up the tester give it a snort of wd-40 or something similar. Supposedly if the rings arent seating/sealing then the lube will help and numbers will jump indicating a problem.
 
make sure it's pulling the little rod on the side of the 3 carbs out all the way. How r u checking compression. You should have all 3 plugs removed, ign. off, hold throttle wide open, & pull it fast 5 times. Try that method & see what u get. Did the cylinders look good.
 
Had all plugs removed with key in off position but didnt have wot. I will try that tomorrow. Cylinders looked great. Infact, you could still see cross hatching in all cylinders. How can I tell if rods are pulling all the way out?
 
blueice2001 said:
I have a 2000 SRX that I just bought used. It has 18000 miles on it but has been taken very good care of. The problem I have is when cold, it is very hard starting. Just a little shot of starting fluid it fires right up. The compression accross all three cylinders was 110. Local Yamaha dealer told me starting issue was due to compression being low so I order new rings and everything to seal it up. After installing rings and running about 5 minutes, while filling and bleeding cooling system I shut engine off and did another compression check, to find same 110 lbs in all cylinders. Also no change in starting, still hard. Does it take more time for rings to seat fully? I am not to famillar with 2 strokes. Any input greatly appreciated.
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Make sure to pull the choke lever to the second position so it flips over backwards from when it is off. If you only pull it so the lever is strait out, it is only half choked.
18,000 is a lot of miles even on an SRX. I just did a complete rebuild on my 2001 that was starting hard last year with 9,000 miles on it and found:
Blown mag side main seal with oil all over the stator, leaking water pump seal, loose fitting pistons and worn out reeds. The reeds should lay closed/flat against the rubber of the cages and not have any chips out of them.
It had 115 pounds of compression before. I've not checked it since the rebuild but...it starts after about 3 pulls when cold and half a pull when warm. This is the easiest it has ever started since it was new.
This sled has been extremely well cared for and got all new pistons with rings, all new seals and new set of stock reeds.

Good luck with your sled.
 
Yea, with 18,000 miles, I would b doing crank seals & water pump rebuild. Just for peice of mind. Although that wont help your starting issue, but i'm sure it's time. You could also check the resistance in the spark plug caps. If they r getting bad, they might not be sparking good when just pulling it over. But it sounds fuel related. BTW, don't use starting fluid on a 2 stroke. It dries everything out. I hope u didn't use it to start it after putting in new rings. That crap will wash down the oil from the cyl walls & bearings. As a side note, MY SRX is a bit hard starting if it sits a couple weeks, let alone all summer.
 
I tore down the motor on the girlfreinds 2000 sxr 700 last year and after putting it all back together I thaught my arm was going to fall of before it finally fired! Carbs werebone dry as I went threw themwhile sled was tore down. Thaught about a snort of either but I just kept pulling till she fired. After that it only takes 3-4 pulls to get it going. Have to restarted a couple times and its a pain every time?
 
I have a 98 and if it sits for a long period it is hard to start. I just pour a very small amount of mixed fuel in the cylinders them once it fires it starts in no more than 3 pulls when its cold.my compression is 130 across the board cold.
 
Stator going bad? I had that problem. Handwarmers are too much for the stock stator. I have a ATV (honda 250r) where a new stator made a night and day starting difference. I don't know how you check the stator though. The resistance check the manual has is bunk, mine was partially melted and it passed the ohm test. Also, I found dust and oil buildup present on the flywheel, further weaking the spark.

Also cylinders are nikasil, so the rings may not be broken in yet. Could be the gauge as other posters have said.

Also, have you tried new plugs? I know it sounds too obvious, but I've fouled many many plugs in my years. Some of them looked ok, but a new set made it start way easier.


edit: i just saw you have a 2000, which has a better stator, so its more likely to be something else.
 
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Tonight I checked compression at wot in 1 cylinder and was still 110ish. I installed the plugs(which were new)and it started in like 5-6 pulls. I can live with that but 20 pulls is a killer for a old man like me. I think I am going to ride it as it is, atleast for this year if it runs half way good and next year pull it and go bigger with it. Cant afford to do much more because I still need to buy a new coat(out grew old one,lol) and a trailer. Anyone got a nice 2 place, preffer a enclosed trailer, for sale near N. IL. for sale? Thanks for all the input and I will be keeping my eyes on you guys here in the threads.
 
blueice2001 said:
When adjusting choke what do I need to look for? All I see in manual is to adjust cable freeplay to between .02-.06 which I have checked.
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what i would do is adjust the choke cable freeplay till it just lets the choke piston return, your not getting the choke open all the way, watch the little choke plungers, and adjust the cable till it releases them just as it returns to the off spot(lever down)
 
Well with that may miles i would of replaced pistons, did you make sure they were within specs? Also it is a good idea to deglaze cyls before reassembling motor. Also you should be checking the ring end gap as well. When bluemonster1 rebuilt his motors last season it took a couple hundred miles for the compression to come up. I believe he had 10000km and his pistons were not within spec.
 
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