First Post: DRZ400 Won't Cold Start

[dukehunter1]

Hi all!  New guy here but I've loved learning a ton from this site so far.  I've had my 2007 DRZ400S for a while now but it's coming out of a 3 year hiatus of being cooped up and untouched.  I've been nursing it back to health and I think I'm about there but I seem to have one last hiccup.  I have a lot of experience working on cars and engines but this has kinda been my crash course for small engines so I'm still learning the in's and out's.

Quick maintenance write-up going over the last month of what all I've done so far:

New battery
New spark plug
Flush/refilled coolant
Oil change
K&N Air Filter
3x3 Mod
Rejetted carb with JD kit, AND rebuilt with new gaskets, hardware, and float valve/needle
I started carb with 25 pilot/155 main/3rd notch on red needle but I could barely keep it running because it would lug down really bad and backfire from exhaust with any throttle (I assumed that meant rich fuel mixture).  So I backed the main down to 150 and it runs just fine now.  

So now the only issue I'm having is that I cannot get it to cold (cold engine, not cold ambient temp) start without giving a quick shot of starter fluid into air intake.  Once it starts, it runs, no problems.  And if I let it warm up for a couple minutes, I can turn it off and start it back up again without missing a beat.  But it just turns and turns when it's cold.  But all it takes is just a little starter fluid and it doesn't even hesitate.

Other vaguely similar problems I've found on the forum seem to have troubleshooting that points to compression (valve clearance check).  Would that problem also not produce similar symptoms even when starting warm?

Thanks so much for any help!

-JD

[shuswap1]

That setup should start but the BRS carb doesn't have an accelerator pump to assist with cold start. I found mine needed a very good crank speed to start easily when cold. Are you certain the choke is coming full on and is the PJ perfectly clean. Any issue with either of these will cause your hard start.

 

[dukehunter1]

18 minutes ago, shuswap1 said:

That setup should start but the BRS carb doesn't have an accelerator pump to assist with cold start. I found mine needed a very good crank speed to start easily when cold. Are you certain the choke is coming full on and is the PJ perfectly clean. Any issue with either of these will cause your hard start.

 

When the carb was off the bike I could see the brass rod for the choke moving through the hole at full and half it looked to be operating correctly.  And PJ is brand new, actually I believe just to be safe I pulled it when I bumped the main jet down just to make sure I could see/blow through it.  I didn't notice any obstructions.

[shuswap1]

OK, idle speed set high enough? I set mine just a little higher than I thought was correct for an easier start and it helped. Does the compression feel decent and is the bike cranking pretty fast? The DRZ needs a fast cranking speed to start quickly, in my experience. Easily checked with a known good batt and jump cables. I'd bet it starts faster using the extra battery, which helps to understand what is going on.

BTW a new PJ can pick up very small debris just as easily as an old one. Just running the issue through, food for thought

[dukehunter1]

23 minutes ago, shuswap1 said:

OK, idle speed set high enough? I set mine just a little higher than I thought was correct for an easier start and it helped. Does the compression feel decent and is the bike cranking pretty fast? The DRZ needs a fast cranking speed to start quickly, in my experience. Easily checked with a known good batt and jump cables. I'd bet it starts faster using the extra battery, which helps to understand what is going on.

BTW a new PJ can pick up very small debris just as easily as an old one. Just running the issue through, food for thought

I haven't touched idle speed yet, but I'll try messing with it a little bit.  When I used to ride every day years ago I didn't have this problem and idle adjustment is in the same place.  Could the fact that I rejetted possibly incline me to need to readjust idle?

Also, I believe I have a compression tester somewhere out in the shop so I'll try that tonight too and see what kind of readings I'm getting.  When it's cranking it sounds like it's in the 300 rpm ballpark.  Is that about where it should be?  It's a brand new battery just acquired a couple weeks ago that I've been putting on a float charger since I've been working on it. 

[CAPT ED]

I would drain carb and fill it with SEAFOAM let it sit a few days and put choke on and crank it a few times everyday to get seafoam thru the choke system, then drain carb fill , with gas and start . Done mine and worked for me .

[shuswap1]

2 hours ago, dukehunter1 said:

I haven't touched idle speed yet, but I'll try messing with it a little bit.  When I used to ride every day years ago I didn't have this problem and idle adjustment is in the same place.  Could the fact that I rejetted possibly incline me to need to readjust idle?

Also, I believe I have a compression tester somewhere out in the shop so I'll try that tonight too and see what kind of readings I'm getting.  When it's cranking it sounds like it's in the 300 rpm ballpark.  Is that about where it should be?  It's a brand new battery just acquired a couple weeks ago that I've been putting on a float charger since I've been working on it. 

These are just a few ideas to narrow down the issue. I'd try the jumper battery and do the comp test warm. Any time you disturb the carb the idle can change. You really shouldn't have to turn the idle speed up....but it has helped mine start just a little bit quicker. No idea on the cranking speed but I do know that if my cranks even a tiny bit slowly it won't go quickly.

[dukehunter1]

Tried again tonight while playing with different combinations of mix and idle screw. Absolutely no luck.  Then I sprayed the starter fluid and it fired right up.  I immediately turned it off so the engine didn't warm at all. Then tried the starter and fired right up. It's like the initial crank isn't getting any fuel to the engine. Gonna try the seafoam as ED suggested to see if the choke channels are clogged or something. 

Also realized I don't have a compression tester so it'll be hard to eliminate that possibility. 

ED, any suggestion on how to keep a carb full of seafoam overnight? And would your method happen to save me the trouble of pulling the carb off the bike? I'm getting really tired of that wrestling match. ?

[ptgarcia]

16 hours ago, dukehunter1 said:

Tried again tonight while playing with different combinations of mix and idle screw. Absolutely no luck.  Then I sprayed the starter fluid and it fired right up.  I immediately turned it off so the engine didn't warm at all. Then tried the starter and fired right up. It's like the initial crank isn't getting any fuel to the engine. Gonna try the seafoam as ED suggested to see if the choke channels are clogged or something. 

Also realized I don't have a compression tester so it'll be hard to eliminate that possibility. 

ED, any suggestion on how to keep a carb full of seafoam overnight? And would your method happen to save me the trouble of pulling the carb off the bike? I'm getting really tired of that wrestling match. ?

Connect a small bottle full of sea foam directly to the carb via the fuel hose.