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View Full Version : Blast is SLOW. What else to check?



adam728
03-15-2012, 05:32 PM
2001 Blast
4000 miles
My sister purchased this last year, all stock except a Vance & Hines exhaust. By all stock I mean even the jetting. Ran quite poorly. Would try and bog off the line unless you babied it, and had a horrendous flat spot at mid throttle / mid rpm.

*New NGK iridium plug
*45 pilot
*172 main (they sent me the wrong 175)
*0.048" needle shim (that's what my washers measured)
*Started with the fuel screw 2-3/4 out, but that was way rich. Bike idles and comes off the line at light throttle much better around 2-1/4 turns out.
*Changed all oil to Amsoil 20W-50
*Adjusted the primary via sound method. Was not easy, doesn't seem to really make any noise even with the bolt about falling out. Have repeated 4 times now, once even trying to just spin the bolt in with my fingers till I felt resistance, then backing off a full turn. That and the sound method seemed to make no difference in, well, anything.
*Removed and inspected the boot. Primo condition. Tried fogging that area with propane while idling to test for a leak, nothing.

It runs so much better now after the carb work. Much smoother, no hicups or hesitation anywhere. But it's dog slow, no difference in wide open compared to before rejetting. Sounds fine, just has very little power. Not that I expect it to be fast, but this thing seems like it has about 20 hp. 5th gear roll on from 60-65 mph takes 10+ seconds. I've gotten it to just break 80 mph, but it takes miles to go from 60-80 mph. I can't imagine jumping on the freeway for any distance with this bike. My old dual sported KDX220 seemed much faster, and stock was only around 28 hp (about 36 hp after a retarded amount of mods).

It sounds like the bike doesn't reach WOT. There's literally no difference from less than 1/2 throttle to wide open. No change in acceleration, no change in engine/intake/exhaust note, nadda. I keep questioning if the CV slide is opening fully, but it appears to be in great condition and slides easily when the carb is removed. Throttle cable slack was triple checked as well.

So, what have I overlooked? Or am I expecting too much? For my sister it probably doesn't matter, most her riding is around town. But I'd hate to see her get out on a longer ride and somehow get in trouble because she can't hardly accelerate from 60 mph. Thought I had it all wrapped up this morning so I could get it back to her this weekend.

Thanks for any suggestions.

brumbear
03-15-2012, 05:58 PM
The engine is to small:p

krjoseph
03-15-2012, 06:11 PM
You've done most of the standard mods, Adam. The next thing would be getting rid of the stock airbox and doing something like the ASB velocity stack/Outerwears filter. Some guys add a K&N filter and cut the excess plastic out of the stock airbox. If you do an intake mod, you'd probably want to go up to 175 on the main jet. Beyound that, guys start adding XB9 jugs, pistons and heads. There's a ton you can do the the Blast, but she's not fast without some work. Good luck.

loose1
03-15-2012, 06:51 PM
Try taking off the airbox and reving it up and see if the slide is moving smoothly all the way up.
Also adding a xb9/12 jug will do nothing their all the same bore. If you want to make them run well, fuel injection is the way to go.
Matt

adam728
03-15-2012, 07:01 PM
So slow might be normal. :D

I know it's not a quick bike, it just seems much slower that I thought it should be. Then again, I've never ridden a street bike with less than ~65 hp! My dual sport was much "quicker', but also weighed <250 lbs and was gearing-limited to about 84 mph.

I'll pull the lid and see if the slide is moving decently. If everything seems mechanically sound she gets the bike back Sunday, and couldn't be happier about it. Told her tonight it was really dog slow accelerating past 60 mph, she laughed and said she'd never had it that fast yet. So big mods won't be necessary.

slabber
03-15-2012, 07:13 PM
Maybe check the compression? You've done all the right things but if it's just down on power, it could just be tired... If the bike was run lean for too long, the rings could be cooked.

pierce
03-15-2012, 08:40 PM
There is something definitely wrong. But if shes happy don't worry about it. At stock you should be able to get up to 80 pretty quickly. Beyond that it will pull a bit slower up to 96.

With a few simple checks, it will keep up with most bikes unless you regularly go over 90. Then good luck, as you will most likely be in jail or in the morgue fast enough.

If you want to keep up with superbikes: do headwork, big bore, different cams - better springs guides and valves and raise the limiter with an SE ignition.

pierce
03-15-2012, 08:45 PM
Also, make sure you are shifting properly. No offense, but this isn't a superbike that can shoot up to 60 in 1st. For protection of the stock engine the limiter clicks in and won't allow you to go any faster in gear. I think its set at 6500? So 60 - 80 is 4th. You may just be hitting the limiter and not know any better. Shifting can be an art form with the Blast.

RuiP
03-15-2012, 09:00 PM
Superbike hits 90 in 1st.

RuiP
03-15-2012, 09:04 PM
Adam you should seriously consider stepping up to an xb9. It's got enough power to get you to speed safely but nothing crazy to scare the bejesus out of you.

pierce
03-15-2012, 09:15 PM
Sweet - it seems like everyone I have ever known that owns a superbike does that too. I think they just don't know how to shift - glorified scooter. I think its also a prerequisite if you own one that you either wear shorts and flip flops, or in a power ranger outfit. I love that crowd.

http://www.youtube.com/watch?v=q0YkXmebAGM

Best thing about that crowd is as soon as it hits 74 they get cold and you won't see them until next year.

adam728
03-16-2012, 03:02 AM
Slabber - compression check will be done, if I can ever find the right adaptor for my gauge! I pulled the plug and got out the gauge the other day in order to check it, but failed. 14 mm end doesn't fit well in a 12 mm plug thread. Maybe a big hammer..... :p

pierce - Not shifting it wrong. I've tried short shifting, stretching a gear out, etc. I've tried to carry 3rd pretty high to see if I was shifting too soon and missing some magical power bubble up high, but by 60 mph acceleration was dropping off, and I saw no reason to abuse it more just to look for a limiter. When hammering on it I go 2->3 at about 35 mph, and 3->4 at about 50->53 mph.

RuiP - No need for an XP9. Just trying to get my sister's little bike sorted out for her. As i said earlier, she laughed when I told her about this, then said she's never been to 60 mph on it yet.

brumbear
03-16-2012, 04:43 AM
Can you data log a blast? I am sorry I never worked on one and don't even know what set up they have. It seems it's flattening the power curve to soon? If it runs strong up to a certain point you can rule out compression more than probably. Valve float? I would honestly lean towards a simple carb malfunction if a blast has one. An ign module malfunction is doubtful but mapping or tps out of parameter is possible I would lean towards timing advance if it's flatening out and there is no fuel delivery problem. Not to be a douche but the fuel filter is clean yes?

turboraven
03-16-2012, 05:38 AM
Simple..it needs an xb12 motor.[up]

pierce
03-16-2012, 06:05 AM
Theres one problem, you would get more power by pushing straight up to the limiter. After all, the limiter won't hurt anything and I often recommend to new blast owners that they should find it in each gear. 2 -> 3 at 35 is going to be lugging the blast engine. You should shift as such:

1 -> 2 around 30 (just before)
2 - > 3 around 50 (etc)
3 - > 4 around 60
4 - - > 80

The powerband for these engine is is the upper rpm, 3500 - 6500. With your shifting the engine would be allways sitting below (and lugging) and working really hard. Shifting prematurely just kills all the power on these bikes. Contrary to what most think, the blasts love the upper rpm and want to be screaming. NEVER shift into second before 30, doing so can hurt the engine.

Hang around the blast forum you will hear riding the limiter a lot. For example J-Lee rides the limiter in 5th around 111 (he got a ticket - sad face) and he can get their really quickly. He also has a video of him showing the accel from stop light to 80 and it takes maybe 6 seconds.

With significant engine work and the SE programmable ignition my limiter is pushed to 8K so I rarely hit the limiter (shift to second around 45, third 60, 4th 80 and I dont go beyond 100 so never hit fifth.) On the on ramp to the freeway I could probably hit triple digits. However, I don't ride it as much as I used to as it has so much customization I use it as my show bike. Its a lot of fun though.

GAXB9R
03-16-2012, 06:46 AM
So slow might be normal.

Probably so wouldn't you think...[cool]

adam728
03-16-2012, 09:33 AM
Theres one problem, you would get more power by pushing straight up to the limiter. After all, the limiter won't hurt anything and I often recommend to new blast owners that they should find it in each gear. 2 -> 3 at 35 is going to be lugging the blast engine. You should shift as such:

1 -> 2 around 30 (just before)
2 - > 3 around 50 (etc)
3 - > 4 around 60
4 - - > 80

The powerband for these engine is is the upper rpm, 3500 - 6500. With your shifting the engine would be allways sitting below (and lugging) and working really hard. Shifting prematurely just kills all the power on these bikes. Contrary to what most think, the blasts love the upper rpm and want to be screaming. NEVER shift into second before 30, doing so can hurt the engine.

Maybe I need to look into timing as well. I can say for certian in 3rd acceleration is hardest below 55 mph. Carry it over that and by 60 mph it's almost stopped pulling. Is the rev limiter a hard limiter that is easily audible, or a soft limiter that cuts spark in a way that you don't really notice? (we make some ignitions that cuts spark, say, ever 6th revalution, then 5th, 4th, etc, so that power tapers off and you don't feel like you are hammering a limiter). This bike feels like anything but a rever, it pulls quite hard in the midrange, then signs off gently. 3rd pulls very well from 40ish to 55.


Please explain to me how shifting to 2nd before 30 will hurt then engine. Is my sister supposed to roll thru her neighborhood in 1st making all sorts of obnoxious racket in 1st?

jetlee
03-16-2012, 09:43 AM
The rev limiter is a soft limiter; it's a spark-skip limiter. If you hit it too hard, you flood the engine (as it's not burning fuel while it skips spark) and it acts like a complete ignition cut until the engine slows way down (pull clutch to drop the rpms fast while keeping the bike under control). If you hit it softly, it's easily audible. It doesn't pitch you forward or anything like that, just stops accelerating.

I used to cruise on the limiter when I had stock ignition. This Ultima has a wicked-sounding spark-skip limiter though.

Shifting too soon is putting a lot of pounding force on the bearing journals. The piston is moving slower and your hammering on it with each combustion. When at higher rpms, the piston is already moving faster so the force transmitted to the journals is less.

Think of it like this: hold a brick in your hand tightly, hit it with a hammer as hard as you can. Hurts don't it? Now, do the same thing, but loosen your grip on the brick so it's already moving a little when you hit it. Doesn't hurt as much, right? Think of the brick as the piston, the hammer as the combustion and your hand as the journals.

jetlee
03-16-2012, 09:50 AM
...and just for shi-grins, I went WOT from 60-65 in 5th this morning. Even with all my mods, it still took me 5-6 seconds.

I rarely run in 5th below 70mph. In stock form, 4th hits the limiter at about 80mph.

The limiter does not hurt the bike. I shifted at the limiter so often it was ridiculous. Hit it, see what it feels like.

Check your air filter and drill a 2nd hole in the exhaust opposite the first (stock) one.

adam728
03-16-2012, 10:47 AM
I understand not lugging it and hammering bearings. I don't understand how running nearly 3,500 rpm in 2nd is "lugging" this bike. Seriously, am I supposed to tell my sister to never upshift until at redline? Heck, look at Buell's suggested shift points (for cruising, I assume).

http://i50.photobucket.com/albums/f346/adam728/Motorcycles/BuellBlastSpeedChart.jpg


The hammer/brick analogy isn't quite right. You'd be hitting the brick faster at higher rpms, not holding it looser. Unless the bearings somehow become elastic. Not that I can think of a better example, but I do know what you were trying to get at.

By the way, nothing to drill in the exhaust, it's a Vance & Hines (stated in 1st post).

pierce
03-16-2012, 10:51 AM
Funny you said that Jetlee - after reading this post I did the same thing. Hadn't been out on the Blast in a while and was a warm day so I took it out for a spin. Tried shifting when he did and the bike just has no power. Usually I am having to slow down for the cars in front of me on the on ramp but this time I felt like I was barely going to make it up to speed - I must admit I chickened out and downshifted.

After you ride it for a bit you'll find the powerband. It likes to scream - sorry. People hear me coming from miles away - children run and hide and parents cover their ears and the Harleys give me the thumbs up. I have tried quieting it down, but its not that much of a concern for me at this point anymore.

http://www.youtube.com/watch?v=q4zyPq6VRls&context=C4f94a94ADvjVQa1PpcFOXCP2ToHbZjSXjTOqse7ca LUCW-qAuQZI=

and thats with a silencer in place ....

pierce
03-16-2012, 10:58 AM
Adam - you have to take what Buell says with quite a bit of salt. After all, its the same company who cubed the bike. They also had beginners in mind, not performance. Their is a difference. Its nice and tame for the most part at stock (keep the rpms down, shift early), and they went to great lengths at keeping people thinking it was a beginners motorcycle and you wouldn't hurt yourself with it. Keep it slow and farty doesn't mean you cant open it up a bit and see for yourself. I sweat they deliberately suffocated the bike to keep it down. All you have to do is let it breathe a bit and suddenly its a different bike.

Looked at the chart again - thats the worst shifting advice I have heard to date. 5th at 45 - 50? 3500 you are just starting to hit the power band, no pull below. Ha ha - anyone else out there that reads that chart, please, dont shift like that, your bike will hate you.

jetlee
03-16-2012, 11:00 AM
If you're running a V&H, get a 175 main jet ASAP!

There have been low end bearing failures. Ask around on BadWeb.

We're talking about Harley's suggestions here....HARLEY! 90% of Harley's are still on the road today, the other 10% made it home! I even come from a H-D dealer family and I despise them. Yet I ride a Buell, I know, no need to point it out.

Regardless, she doesn't need to wind it out, but she should be running it at higher rpms for reliability.

You wouldn't be hitting the brick faster (harder) at higher rpms, you'd be hitting it more often in a given time period. My analogy for was a single power stroke. You got my meaning though, so it served its purpose.

adam728
03-16-2012, 02:54 PM
It sounds like the bike doesn't reach WOT. There's literally no difference from less than 1/2 throttle to wide open. No change in acceleration, no change in engine/intake/exhaust note, nadda.* I keep questioning if the CV slide is opening fully, but it appears to be in great condition and slides easily when the carb is removed.

Dumb dumb dumb

Should have listened to myself. Spent too much time making sure the cap and diaphragm were in place, and not enough time making sure the spring was in the right place in the cap! Sure enough, was only opening about 1/2 way. Test ride tomorrow.


Really feeling like an idiot. Used to work as a certified bike mechanic, now am an engineer that works on carbs for a living. Should have not made this mistake. [sad]

brumbear
03-16-2012, 04:15 PM
Glad you got it sorted hey I spent 2 days on a loose condenser not to long ago no worries we all overlook stuff!!!!!!!!!!!!!!

jetlee
03-16-2012, 04:37 PM
I've forgotten to reconnect the fuel line. I even turned the petcock on before I took off. When it died down the road, I was dumbfounded till I looked down at all the fuel pouring out.

We all miss stuff once in a while.

adam728
03-16-2012, 05:58 PM
Rev limiter, 1st thru 4th, no problem at all. Lifted at 90 in 5th. It's still slow for a bike, but it's twice as fast as it was![up]

pierce
03-16-2012, 06:43 PM
Good to hear.

What do you ride normally?

adam728
03-16-2012, 06:49 PM
What do you ride normally?

Dirt.

I've had a 77 CB750 Super Sport, 83 Nighthawk, then worked at a Victory dealer thru college and generally had a Vega's demo bike, or various used trade-ins to play with. Probably the slowest (and most fun) street bike I've spent time on was a Interceptor 500. Narrow, light, and nimble!

Right now I only have a 05 YZ250 in the stable. Started getting parts in this week to dual sport it. Plan is just to open up new trails, probably won't see much, if any, pavement. Wife gave me permission for a street bike, but no money. :o

pierce
03-16-2012, 07:09 PM
Love the CB's. That used to be my goto cafe until I went on the hunt for a single cafe. Dual sports are cool too. I seem to own one bike for every function. However, the ballsiest bike I own is the blast. I have probably spent way too much on i (time and money)t, but I love wrenching.

Good luck on the street bike!

ezblast
03-17-2012, 06:42 PM
I understand not lugging it and hammering bearings. I don't understand how running nearly 3,500 rpm in 2nd is "lugging" this bike. Seriously, am I supposed to tell my sister to never upshift until at redline? Heck, look at Buell's suggested shift points (for cruising, I assume).

http://i50.photobucket.com/albums/f346/adam728/Motorcycles/BuellBlastSpeedChart.jpg


The hammer/brick analogy isn't quite right. You'd be hitting the brick faster at higher rpms, not holding it looser. Unless the bearings somehow become elastic. Not that I can think of a better example, but I do know what you were trying to get at.

By the way, nothing to drill in the exhaust, it's a Vance & Hines (stated in 1st post).


Thats for break in =
EZ