View Full Version : got a ? for ya...this is F'd up
400thacker
02-16-2008, 07:06 PM
well got my quad all together again after honda ordered the wrong rings and i installed the rights ones. put the stock cam in it thinking that MAYBE it would start easier. I was wrong.
i put everything where it needs to be including the time and pulled it behind my truck and tried to start it. only pops and fire out of the head. it sounds like it is running but it's definately not producing any power at all and i am sure i shouldn't be seeing all that fire comiong out of the head. i don't have the header on right now, just trying to get it running first. every once in a while it would hit 2-3 times and try to take off but it wouldn't start. any ideas? has lots of compression and good spark and the timing marks are lined up and the piston it TDC when the T lines up on the case side. i don't know WTH is wrong. I want to burn it as it sits:grr: :grr: :grr:
it has fresh gas too along with a new spark plug. could the CDI be firing at the wrong time?
should i just move the timing chain one tooth at a time till it starts...seems like my only option
Originally posted by 400thacker
well got my quad all together again after honda ordered the wrong rings and i installed the rights ones. put the stock cam in it thinking that MAYBE it would start easier. I was wrong.
i put everything where it needs to be including the time and pulled it behind my truck and tried to start it. only pops and fire out of the head. it sounds like it is running but it's definately not producing any power at all and i am sure i shouldn't be seeing all that fire comiong out of the head. i don't have the header on right now, just trying to get it running first. every once in a while it would hit 2-3 times and try to take off but it wouldn't start. any ideas? has lots of compression and good spark and the timing marks are lined up and the piston it TDC when the T lines up on the case side. i don't know WTH is wrong. I want to burn it as it sits:grr: :grr: :grr:
it has fresh gas too along with a new spark plug. could the CDI be firing at the wrong time?
should i just move the timing chain one tooth at a time till it starts...seems like my only option
You're running it without the header and you're wondering why flames coming out of the head?
REPOMAN
02-16-2008, 07:40 PM
put your exhaust on and try. mine was hard starting without mine on aswell
ROFL your going to burn out your valves. Your quad isnt going to run right without headers theres no back pressure at all.
416exfreak
02-16-2008, 08:17 PM
Wow...try putting an exhaust on.
At least the header....:huh
drew416ex
02-16-2008, 09:14 PM
YEah, with no back pressure you can forget that think running. Also, if you didnt re adjust the valves when you put it back together, they may be slightly open causeing loss in cylinder pressure. Thats what happened to me once anyways.
wifehatesit
02-17-2008, 08:31 AM
DO NOT MOVE THE TIMING CHAIN ONE TOOTH AT A TIME!!!!
UNLESS IT IS A NON-INTERFERENCE MOTOR, THE PISTON WILL HIT THE VALVES AND BEND THEM THEN U NEED A HEAD JOB!
When you put the stock cam back in did you install the decompression spring and plunger?
xcracer416
02-17-2008, 11:30 AM
is the plug fouled? if it is then you very possibly have a sheered flywheel key
scruff_mcruff
02-17-2008, 11:36 AM
Originally posted by FoxHondaRider
ROFL your going to burn out your valves. Your quad isnt going to run right without headers theres no back pressure at all.
congrats you nailed all the misconseptions of the net in one statement.
You WONT burn up any valves by not having an exhaust on. the engine dosnt know theres no exhaust till after the burn stroke takes place, so the temp in the cylinder will be the same regardless.
Then back pressure is not a good thing, on single cylinders its used to help design a specific power curve, but look at the top performers in exhaust shootouts. the ones on the top are always the loudest= least amount of air restriction.
400thacker
02-17-2008, 12:11 PM
i joking about going one tooth at a time. that would have about 3 months.:D
I have run them before without a header to get them started and didn't have any problems. what i was saying about the exhaust shooting fire is "that" tells me that i am getting gas and spark or else it wouldn't do that.
i think it sounds like time but how is that possible when all the marks line up? and the piston is exactly TDC when the t lines up so does that mean the key isn't sheared?
what about the CDI, could that be the problem?
TRXRacer1
02-17-2008, 01:19 PM
Originally posted by scruff_mcruff
You WONT burn up any valves by not having an exhaust on. the engine dosnt know theres no exhaust till after the burn stroke takes place, so the temp in the cylinder will be the same regardless.
Then back pressure is not a good thing, on single cylinders its used to help design a specific power curve, but look at the top performers in exhaust shootouts. the ones on the top are always the loudest= least amount of air restriction. In the same statement you mention the engine not knowing what's after it and you shared an equation relating air flow to noise. I'm not going to comment on the valves but do you really think running without an exhaust doesn't change anything? He's leaning out the air/fuel mix setting up a condition that can lead to overheating and detonation. If his jetting was anywhere near the lean side to begin with he would, without any doubt, have a problem with not running the exhaust. I mean he could have bad gas or a crap plug for all we know but to say it won't effect cylinder conditions is flat out false.
drew416ex
02-17-2008, 01:56 PM
Originally posted by TRXRacer1
In the same statement you mention the engine not knowing what's after it and you shared an equation relating air flow to noise. I'm not going to comment on the valves but do you really think running without an exhaust doesn't change anything? He's leaning out the air/fuel mix setting up a condition that can lead to overheating and detonation. If his jetting was anywhere near the lean side to begin with he would, without any doubt, have a problem with not running the exhaust. I mean he could have bad gas or a crap plug for all we know but to say it won't effect cylinder conditions is flat out false.
X2
400thacker
02-17-2008, 07:26 PM
ok guys...what should i do besides mounting up the exhaust?
scruff_mcruff
02-17-2008, 07:47 PM
Originally posted by TRXRacer1
In the same statement you mention the engine not knowing what's after it and you shared an equation relating air flow to noise. I'm not going to comment on the valves but do you really think running without an exhaust doesn't change anything? He's leaning out the air/fuel mix setting up a condition that can lead to overheating and detonation. If his jetting was anywhere near the lean side to begin with he would, without any doubt, have a problem with not running the exhaust. I mean he could have bad gas or a crap plug for all we know but to say it won't effect cylinder conditions is flat out false.
you need to remember we are talking about no load on the motor so theres ALOT less fuel requirements for idling and revving up than a 4th gear pull. it would be a different story if your gonna run no header and go out and race. but thats not the topic. and he said he has fresh gas and a new plug.
and go spend some time with an EGT gauge and you might start to learn something.
scruff_mcruff
02-17-2008, 07:53 PM
Originally posted by 400thacker
ok guys...what should i do besides mounting up the exhaust? recheck your cam timing, the 400s can be alittle weird. my 99 was fine but my gf's 01 was offset a little. i had the exhaust side lined up but the intake side was 1/2 tooth low and it wasnt right, so it ended up beeing the intake side on and exhaust side 1/2 tooth low. and make sure you check that with the tensioner on the chain cause that will move it alittle.
400thacker
02-17-2008, 09:55 PM
i don't really follow you on the 1/2 tooth off thing...i can't afford the $70/hr to have it worked on at a shop and with something like this they can't tell me what the charge would be or even give me an estimate.
so what you are saying is that if the piston is TDC and the cam marks line up then it can still be out of time?
Originally posted by JOEX
When you put the stock cam back in did you install the decompression spring and plunger?
400thacker
02-18-2008, 01:09 PM
no i didn't but does that matter? just makes them harder to start right? i didn't use it with the TC cam and it ran before
lorenjr83
02-18-2008, 01:40 PM
Originally posted by 400thacker
what about the CDI, could that be the problem?
that could be your problem. i let mine sit for 3 weeks while on vacation and it would start. i had to swap cdi's with another 400
400thacker
02-18-2008, 02:38 PM
can the CDI be bad if you are still getting spark?
and...does it matter if the third mark on the cam timing gear is facing down instead of up? i thought it was the same either way.
drew416ex
02-18-2008, 02:45 PM
As long as the lobes are facing down when you have it on "t" it doesnt matter if that mark is up or down. Otherwise the valves are open on compression stroke.
Originally posted by 400thacker
no i didn't but does that matter? just makes them harder to start right? i didn't use it with the TC cam and it ran before
As far as I know when using the stock cam the motor will NOT start without the spring & plunger. I also belive most aftermarket cams do not require the use of the spring or plunger.
400thacker
02-19-2008, 10:58 AM
well, i am running a tc 924 cam and it has the decompressor on the cam but i am not using the plunger or spring, should i remove the decompressor on the cam? are you sure this can keep one from running?
i appreciate the help on this guys.
Originally posted by 400thacker
well, i am running a tc 924 cam and it has the decompressor on the cam but i am not using the plunger or spring, should i remove the decompressor on the cam? are you sure this can keep one from running?
i appreciate the help on this guys.
I'm not sure on the TC cam but if it has the decompressions lobe i'd try it with the spring & plunger.
chris46250r
02-19-2008, 11:50 AM
Who knows whats wrong now considering you could have it out of time and you've pulled it behind your truck.
400thacker
02-19-2008, 01:06 PM
well thats the problem...i lost the spring.
can i just remove the decompression lobe from the cam? that would do away with that problem right?
i had everything where it should be with the timing so it couldn't have messed anything up in the motor by pulling it. as long as the valves dont hit the piston what could it possibly do?
lpmaster
02-20-2008, 12:09 AM
you need to begin ruling things out.
1- motor at tdc marks on cam sprocket are
_ | _ and the 2 horizontal ones are parralel with the head.
2- you dont need the plunger even with the stock cam.
3- triple check spark and make sure it isnt a weak spark. check by taking the plug out of the head. and crank the motor with the plug wired up and touching a ground.
4- if all is good and valves are adjusted to spec. spray some starting fluid in and see if you can get it to fire and idle. if it fires but wont idle all your headaches have been cause by jetting.
5- i have a stock 05 cdi box i'd send you if you needed one for the price of shipping. which could be a culprit of weak or no spark.
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