Want more power from your 2010 TC250 and a surprise from the Husky factory!

Today we fitted a Boyesen Quickstart QS3 on one of our team 2010 TC250 bikes. This bolt on trick kit is supposed to serve two purposes: 1) it apparently makes starting hot 4 stroke engines much easier and 2) gives the ability of tuning the Leak Jet by an adjustable screw. The stock Leak Jet for the bike is 35 and we wanted to adjust it to 60 since we had heard good reports for this setting. This meant turning the screw just over 1.5 turns from the closed seated position which is what we did.
we removed the cover off the accelerator pump and were shocked to find the timing screw had ALREADY been modified!!! The nipple at the end of the screw had been removed to reduce the original factory setting gap and tied back with a piece of wire very similar to the O ring mod already mentioned on this forum!!! This apparently increases the petrol spray timing from approximatly every 2 to 3 seconds to every second. So WHO did this as this was a brand new bike just recently imported from Australia??? Well it certainly wasn't the Aussies as I spoke to them about it, so it must have been done in Italy! Maybe the Husky technicians finally realized this and started doing it to the bikes on the production line??? Now IF that was the case and IF some of the test bikes were from an earlier production and didn't have this mod done then this COULD account for some of the inconsistency we are seeing!?!?
OUR RESULTS: First of all the bike was a LOT more DIFFICULT to start!!! Not what Boyesen claims with their money back guarantee!!!
Regarding the power though we noticed a HUGE gain in overall HP especially towards the TOP end!!! In fact the whole ride was MUCH more responsive, noticeably different, AWESOME!!!
CONCLUSION: The Boyesen Quickstart method did NOT work for the TC250. After making sure that the Timing screw mod had been done to reduce the gap to 0.115" (ours already had this probably from the factory) changing the stock 35 Leak jet to 60 GREATLY improves the overall power of the bike especially in the top end!!
I would highly recommend that any serious 2010 TC250 owner opens the AP cover on the float bowel and checks if their Timing Screw has already been modified which is easy to see if it is tied back with a piece of wire, I will post a pic below.
Please post your results to this forum as it is very interesting to know how many bikes have or have not yet had the Timing Screw modified!
WHAT WE WILL TRY NEXT: If we can't get the bike to start more easily we will try a Merge adjustable Leak Jet Kit! I will post the results once we get this far!
Thanks

Here's the mod already made to the Timing Screw (notice the bit of wire)!

I'm using an O-ring and getting much better throttle response overall. I'm confused why the leak jet is having anything to do with starting or top end performance? Starting should be a function of pilot jet and fuel screw settings. Also, why would the AP mod affect top end which is a function of main jet and exhaust and valves (among others)? The AP mod should effect throttle response and help eliminate bogging on quick throttle twists.

the internet..................................its wonderful place to learn new things

please post a foto of your 2010 TC250, we love new bikes here.

It would be interesting to learn who wired the AP linkage. Surely not the factory!!??

some good mechanic also bent the cable retainer slot as well

ps those vent tubes have that factory new color racing style look too. Hope your team makes it to the MX of Nations.

I don't think the leak jet has anything to do with the starting issue, the problem here is the hot start system used by Boyesen, it just doesn't seem to work well for the TC...The throttle responce yes, just seems to work all the way up the band!

So you tried the QS3 Quickstart... not just the QS3? I've read some things about the Quick Start QS3. It basically shuts down the accelerator pump when it's actuated, which makes no sense in a hot start condition because you shouldn't be twisting the throttle while starting a hot four stroke anyway. Either way, I still don't understand how bolting the Boysen to your carb had any effect on starting unless you're pulling it when starting cold and it's not allowing a squirt of fuel into the throat. My cold start procedure assuming my fuel screw is set properly for the temp and alt is choke on, one quick turn of the throttle to get some raw fuel in the throat, and a smooth, firm kick from TDC or one click less and she fires in one kick 99% of the time. Although, I must admit, when the temps hit the 30's (F), I had to tweak the fuel screw setting about 1/4 to 1/2 further out after having a few 3 or 4 kick cold starts.

Ok I am still a little sleepy but as I understand yours was wired back from the factory right? Ok did you remove the wire and now it pulls better or did it pull better with this mod? Little help please. Oh yes thanks for sharing.

Did the same mod to 02 yzf 250 and it wouldn't start worth a crap until I read about changing the leak jet to a bigger one on TT, once I
installed the new jet the bike started much easier, also had to mess with the main jet cleaned up the low speed bog I was exspeancing my .02

Ok. I guess I really need to go back to carb school. Can someone please explain to me what the he!! a LEAK jet has to do with starting a four stroke bike??? I must be missing something, but doesn't the leak jet control the amount of fuel bypassed to the bowl when the throttle is whacked?... therefore decreasing the amount of fuel introduced at the AP nozzle when the throttle is whacked? Everything I've ever read suggests this is the case. If I'm right, then the only possible explanation for a bigger leak jet helping starting performance is the chance that the rider is whacking the throttle while kicking, and the bigger leak jet is not allowing as much fuel to the throat thus lessening the chance of flooding???? IMHO if any 4 stroke rider whacks his throttle while starting (except for a twist or two prior to kicking while cold) that rider is probably not schooled on how a 4 stroke carb works. But, as always, I could be missing the forest for the trees. Please, someone, educate me.

the problem is starting it HOT. Boyesen says that it doesn't matter if the throttle is cracked when trying to start it hot. We have tried both, cracking it open and keeping it closed but still no luck...our temperatures here are 30c plus so maybe adjusting the fuel screw a bit further out? Any suggestions??

Boysen is telling you that because their quick start system disables the AP when it is pulled. If you've taken the Boysen off and still whacking the throttle, you're dumping raw fuel into the carb at the worst possible time... when the engine is hot. Four strokes tend to get really hot and will "soak" the motor with heat when you shut it down. This tends to displace oxygen in the carb creating an overly rich condition when starting hot. This is why you should never whack the throttle during a hot start. Conventional hot start levers operate a valve in the carb that introduce more air into the carb. So basically, under hot start conditions, you need more air and less fuel. By turning the fuel screw out, you introduce MORE fuel into the pilot circuit when you need less fuel. When it's hot, you normally need to turn the fuel screw in. It sounds like your bike is probably jetted too rich in the pilot circuit including the fuel screw. 30c is not overly hot, but other factors such as altitude and humidity may "stack up" and make things worse. If you're hot, humid, and high (altitude) you're bike is probably running very rich due to less oxygen available per volume of air.

Good read Krieg. So does the wired linkage add top end power or do you need to take it off for increased top end power? I am still unclear on this or what the OP did to increase top end power.

All the wire (or O-ring) does is change the timing and duration of the squirt of fuel provided by the accelerator pump when the throttle is twisted. If there's no throttle motion (i.e. steady throttle and no twisting), the AP linkage and the AP are not in play. Thus at WOT there's no further fuel contribution from the AP. I'm saying the wire is only enhancing throttle response and "hit" and couldn't be contributing anything to the top end. Possibly people are confusing the better response and bigger hit as "top end"?

That make sence thanks for clearing that up. My son's bike has clean pull all the way to the rev. limiter. We do have the SA (spark arrestor) removed and it looking at the SA it does seem a little restrictive but we didn't even run the bike with it in. Is the SA still in your bike? How does your top end power feel?

My arrestor is out. I've got an O-ring on the AP linkage and it improved throttle response. I tried the wire but got a slight stumble when making minor throttle changes which I attributed to the AP being overly sensitive and richening things too quickly. The O-ring allows for a slight delay and seems to be the ticket on my TC. Top end has never been an issue for me since I will never ride the bike close to its capability. I think the mid is the best I've ever ridden.

Well, I guess I should pick up an Oring so I can install when I get the bike. Could you please tell me what size/# Oring I am suppose to use? Thanks!

Blake