| Author | Message | ||
     Thrive2drive |
My 04 Blast is fully stock, as far as I know, about 2K miles, and I'm having issues with the bike "bogging down" when I give it full throttle while riding. In neutral or with the clutch engaged I can rev it all the way up but once riding if I give it like more than a quarter throttle it bogs and hates life. It does it in every gear. Even though it seems to be something y'all are against, I rebuilt the carb, new diaphragm bc the old one was really stretched out and new gaskets and it solved nothing. Growing up we had snowmobiles so I'm no stranger to taking carbs apart, but this is my first bike. Any thoughts? | ||
| Gearheaderiko |
It's not the point that the carb is complicated, just a rebuild is hardly ever needed: "it solved nothing". Yep!! And at an alarming rate, "giving the carb a good cleaning" usually causes more problems. You say it's stock, but doesn't have the original engine-that's not really stock. So: what was the jetting in the carb? Has the idle mixture screw been uncapped? What were the settings on the carb? Besides not having the original engine is everything else original or "bone stock"? Original exhaust? All safeties intact? Has it ever run right for you or did you buy it running this way? Do you have any idea what the actually mileage on the bike is? Why did they change the engine? Is it a California bike? Besides pulling the carb apart, have you done anything else at all to your Blast? | ||
| Thrive2drive |
I'm assuming it's a different motor bc the bike was laid down, that's the only reason I could think of. The frame is a 2003, motor a 2004, odometer says 2K but who really knows. The bike was an old man's end of life crisis he bought new and rode for a few years, laid it down a couple times and decided not to ride anymore, so it was in a barn for like 8 years before his grandson took it out. That's who I bought it from. As far as he knew the bike ran just fine before garaging it. I knew it was a gamble buying the bike, but for $900 I thought it a decent deal and I was up for tinkering on it. Since the bike had not run in such a long time I drained all fluids, thankfully they looked decent and not watery or anything. I also took the carb off, it did have some gunk in there that I cleaned out, jets were clogged, and the float was sticking. Got that all sorted as well as cleaned the tank. I have no idea how to tell if the jets are original size. Stock exhaust. Stock intake. Everything appears to be in place and original (except motor) and I did install a "Super Boot" to replace the stock one (bogging was there before and after installation of super boot). Idle Mixture is uncapped, I did that after seeing on here it was recommended, I followed the steps that I believe EZ posted. As far as carb "settings," what do you mean? Its not shimmed or anything and the angle of the float it normal. The bike has done this bogging down ever since I got it running. At first I thought it was the rev limiter, but it was happening at such low RPM that I knew it couldn't be. And no, the bike has always been in Texas as far as I know. | ||
| Gearheaderiko |
Okay, we'll make some assumptions: indications from the uncapped mixture screw is the carb has been unmolested. Slow/pilot jet should be changed to a #45. Engine mileage is unknown. Change the spark plug and make sure the gap is .038-.043 Check the primary chain tension. VERY common cause of bogging. Because the repair manual instructs to adjust the chain too tight, this happens A LOT! Manual says 4-7 flats out, should be 12-20 flats out on the adjuster bolt. Rev limit in 1st gear is about 32mph. It should reach that fairly quickly (but not wheel popping quickly). This is a bike with 34hp stock and a vacuum piston carb without an accelerator pump. It makes its power in the upper rpm range. It's no stump puller!! it's also not a rocket and twisting the throttle isn't likely to make it jump-just to be sure you're not expecting more from this bike than its got. | ||
| Gearheaderiko |
Let us know what you find out. Thanks. | ||
| Thrive2drive |
Haha, thanks for the info, and yea I've heard the bike isn't exactly Salt Flat material from the factory, which is honestly why I wanted is as a first bike. I'll go ahead and order a #45 jet since I do not know whats in there. I did already swap out the plug, forgot to mention that earlier, but I'll double check the gapping. I never touched the primary chain tensioner so I will check on that and let you know what I find out. Thanks! | ||
| Thrive2drive |
Spark plug gap was fine and I checked the tensioner, did it the 12-20 flats method didn't change anything. Then I did the sound method, got a little better, didn't bog in first at all but did the rest of the gears. I've got new jets on the way, heard shimming the needle .05 or so is something people do as well, but we'll do just the jets first. I'll keep you posted, thanks for the help so far. | ||
| Gearheaderiko |
Better to do things one step at a time, especially if you are trying to solve a problem. | ||
| Gearheaderiko |
There's a lot of things I could list, but start with most likely first. If fixed, The rest then would be considered mods, not cures. | ||
| Thrive2drive |
Sorry, busy holidays and had been away from the bike. Got new jets installed and double checked everything, still bogging at too much of a throttle increase. As much as it pains me I'm tempted to find a shop and take it there, but it feels like it could be something so simple I'd hate to get raped at a shop for something I could do myself.. | ||
| Gearheaderiko |
You'll get raped and you probably know more about the Blast than they will. They'll very likely charge you for another unnecessary carb rebuild, which again will fix nothing. At this point I'll assume somebody F'd something up and it's not just a wear/part failure problem. Next step would be to check the timing. The static method in the book is fine to do if you dont have a timing light. If you have a timing light-do both. MARK THE ORIGINAL LOCATION OF MODULE. This can be done with paint or a scratch mark. (If you use a timing light, you'll need a clear hole plug for the timing hole. It's a standard Harley item about $5-$20. If you don't use it, you will get oil everywhere!) I would do a compression test. I'm doubtful this is the problem, but it would sure be helpful to know it isn't!! Knowing what the compression reads would also be helpful. Questions (check the timing): Will it redline in first gear which is about 32mph? | ||
| Thrive2drive |
Haha, yea you're probably right! I've got a timing light so I'll check it this weekend. Thanks, I'll let you know what I find out. | ||
| Thrive2drive |
Haven't had a chance to check the timing yet, but on my last two rides the bike ran beautifully, I had full power right from the get go in all gears, it's fantastic. I have no idea why, but I'm not complaining, maybe it was just getting used to running again. It actually has more get up than I originally thought haha. I'll keep y'all updated, probably check the timing just for fun. |
