Hard Starting 450

[Stickman400]

My 450s been sitting in the corner of the shop (heated shop btw) for the last 4 or 5 months without being started. All last summer after I first bought it, it would start up with 1 or 2 kicks after sitting for a month or more if you just pulled the choke and pumped the throttle 2 or 3 times. Now after this winter I can't get it to start for nothing via kicking it. I have to have my dad pull start me, and then it runs fine. Even if you kill it immediately after getting it pull started for the first time in a couple weeks it will fire right back up in 1 kick, but if you let it sit for a few hours an let it get cold it won't start and you'll have to pull it again. After you get it started it runs just like it did last year, perfect. No hiccups, sputters, backfires or hesitations. So I'm thinking maybe the plug just needs changed and the carb. needs cleaned and some fresh gas, but I'm just curious if there any other little things that these things are picky about and won't start due to it. I'm no 450 expert so I'm coming to you guys. Thanks!

[quad71]

Sounds like you need new intake valves. How many hours on engine. I replace my intakes every 40 on a 09.

[CJM]

Yup valves. Either shim or replace them (Id replace if it has a good bit of time on it).

[Rat-A-TatRacing]

Valve adjustment should fix your prob. Sounds like there not closing all the way and then when she warms up the metal expands and the gap closes. That y she fires so easy after she warmed up

[Stickman400]

As far as I know the entire engine is stock from the factory parts. But that's just what my friend that I bought it off of was told. I've adjusted the valves once and it was nice and quiet and ran fine all last summer. Then it started doing this over the winter. I'll try adjusting the valves again and if that doesn't solve it I'll know what to do, but I got other toys I'm puttin' money in so this'll have to sit in the corner and gather dust for awhile. Thanks guys.

[blacknblue#2]

If the quad started fine when it was parked 5 months ago then started acting up after setting dont worry yourself into valves just yet. Yes when a 450 become hard to start generally out of nowhere its the valves but a machine that been setting adn not running wouldnt necessarily be the case. Valves dont wear by settin there doing nothing. I would start with all fresh gas and a carb cleaning....Focus on the pilot jet circuit. This is the starting circuit. The pilot circuit aint as critical on a warm engine.. was there gas in the carb while it set? anytime a quad is gonna set i sugguest turning the gas off and let it idle untile it runs itself out of gas

[2001400exrida]

I agree with blacknblue, probably not the valves with this scenario. Get a good day of riding in and make sure your carb is clean. It sounds like your pilot jet may have a little gunk in it making it hard to start. I've had my trx450r for 2 years and have never set the valves and it still runs perfect. Also, if it doesn't have alot of hours you don't have to replace the valves, you can shim them a couple times usually before they need replaced. Hard starting does usually lead to valve settings, but not always especially not in your case where it ran fine before you parked it and then you let it sit for some time.....Give a good days riding and a good carb cleaning and plug change and see how it runs.

[LeGaCyGiAnT124]

I agree with blacknblue, probably not the valves with this scenario. Get a good day of riding in and make sure your carb is clean. It sounds like your pilot jet may have a little gunk in it making it hard to start. I've had my trx450r for 2 years and have never set the valves and it still runs perfect. Also, if it doesn't have alot of hours you don't have to replace the valves, you can shim them a couple times usually before they need replaced. Hard starting does usually lead to valve settings, but not always especially not in your case where it ran fine before you parked it and then you let it sit for some time.....Give a good days riding and a good carb cleaning and plug change and see how it runs.

My 450's intakes somehow tightened up from sitting this past year. Long story short my 450 sat from August to January before I tried firing it up. I changed out the gas, cleaned the carb, and tried firing it. Kick, Kick, Kick, nothing. I ended up getting it to run bump starting it. My intakes tightened up to a point where I needed a new valve job. The weird thing is that it would fire first kick the last time I rode it. Some things just happen.

-Brandon

[Stickman400]

Well that is very odd. I'll try and get a good ride in on it and clean the carb., change the plug and run some fresh gas through it. Hopefully it is just that and doesn't need a valve job.

[CJM]

Interesting scenario legacy, never heard of such a thing.

[LeGaCyGiAnT124]

Interesting scenario legacy, never heard of such a thing.


I am not saying thats exactly what happened, but that's what it seems like to me. I don't tear into the valve cover unless I A. Have an unusual tapping noise coming from the top end or B. Have cold start starting issues. I didn't have any issues last summer. It just seemed to tighten up on me over the winter months lol. Didn't you know that metal expands to tighten the clearances during the colder months :huh:blah:

[CJM]

yup metal expands when cold lol..

[Stickman400]

Well I finally got around to dragging the 450 out of the corner and tinkering with it. I adjusted the valves and found the intakes tight and the exhaust perfect. So I dropped the left intake .05 and it was good at a 1.55 from a 1.60, but I dropped the right intake to a 1.20 (the smallest one made) from a 1.40 and I still couldn't get a .005 feeler gauge in there (since it's .006 +/-.001). So I don't know what the problem is there. I may need a valve job sometime too. Then I cleaned the spark plug since I didn't have a new one and then put it in with di-electric silicone on it. Then I pulled the bowl off the carb. and looked through the main and didn't see anything, bowl was also spotless, so I just sprayed carb. cleaner through the pilot and re-assembled everything. I pulled the choke and kicked it over without pumping the throttle and it fired right up 2nd kick just like it used too. I'd say it was the plug that was the problem but the intakes may have been making it worse also. Thanks for the help guys!

[LeGaCyGiAnT124]

Well I finally got around to dragging the 450 out of the corner and tinkering with it. I adjusted the valves and found the intakes tight and the exhaust perfect. So I dropped the left intake .05 and it was good at a 1.55 from a 1.60, but I dropped the right intake to a 1.20 (the smallest one made) from a 1.40 and I still couldn't get a .005 feeler gauge in there (since it's .006 +/-.001). So I don't know what the problem is there. I may need a valve job sometime too. Then I cleaned the spark plug since I didn't have a new one and then put it in with di-electric silicone on it. Then I pulled the bowl off the carb. and looked through the main and didn't see anything, bowl was also spotless, so I just sprayed carb. cleaner through the pilot and re-assembled everything. I pulled the choke and kicked it over without pumping the throttle and it fired right up 2nd kick just like it used too. I'd say it was the plug that was the problem but the intakes may have been making it worse also. Thanks for the help guys!

Were you able to get any size feeler gauge in the one intake? It sounds like you do need a valve job. You're looking at $250-300 for parts and labor for the valve job.

[Stickman400]

I tried a .003 and it wouldn't fit but I didn't want to try a .002 because it was like trying to shove a piece of paper in there. It's so thin it just bent the feeler gauge over before it got in there. I'm planning on tearing it apart and rebuilding the entire top end eventually. Piston/cylinder/cam/oversized valves/port and polish/possibly a 5 angle valve job, but I don't have the money right now and I only ride it maybe 4 or 5 times a year as it is so it can wait.

[LeGaCyGiAnT124]

I tried a .003 and it wouldn't fit but I didn't want to try a .002 because it was like trying to shove a piece of paper in there. It's so thin it just bent the feeler gauge over before it got in there. I'm planning on tearing it apart and rebuilding the entire top end eventually. Piston/cylinder/cam/oversized valves/port and polish/possibly a 5 angle valve job, but I don't have the money right now and I only ride it maybe 4 or 5 times a year as it is so it can wait.

Money issues always get the best of me too lol. I want to try aftermarket valves and springs, but never have the cash when it comes to it. Always have used the OEM ones but can't get much life out of them.

[DnB_racing]

Money issues always get the best of me too lol. I want to try aftermarket valves and springs, but never have the cash when it comes to it. Always have used the OEM ones but can't get much life out of them.these only a couple reasons you wont get much life from oem
one reason poor maintaince (oil changes)
another is bad fuel
and dirty air filter or dirt getting through your air filter

[LeGaCyGiAnT124]

these only a couple reasons you wont get much life from oem
one reason poor maintaince (oil changes)
another is bad fuel
and dirty air filter or dirt getting through your air filter

I maintenance my quad all the time. I change my motor and transmission oil every race or every 4-6 hours of play riding. Clean my airfilter when it's dirty, and put new fuel in every time I ride it. I got 30 hours on my last set of valves and springs from a handful of races and trail rides. I have a feeling I know why they went bad so fast on this set. I sunk it at one of the races and had an air leak issue that year.

It took me a few races in to figure out that my intake boot wasn't sealed properly on the carb. I have a method now of putting the carb to the boots right now. Loosening the airbox makes it 10X easier to put on and make sure that it is tight.