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1250 Performance Mod Questions

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May 30, 2009
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OK, I'm a noob when it comes to performance increases on FI engines. I'm also in the beginning stages of saving up to get the most I can out of the 1250 motor without replacing innards. Since it will be quite some time until I can afford to completely upgrade everything currently available, I'm trying to determine two main things:

1) Which of the "free" performance upgrades can be made before a TFI or PC is needed?
2) If operating on a budget, which performance upgrades provide the most bang for the buck, and what would be the proper order in performing them?

I plan to eventually upgrade my entire system, most likely with Dale Walker's complete Holeshot system, but if there's anything I can do in the meantime (i.e., free) until I save up the $$, I'd like to take care of it now.

Performance Mod (Cost)

1. Remove secondary butterflies (free)
2. Block/remove PAIR valve (free)
3. Modify air box cover (free)
4. (Is this where the TFI/PCIII is needed?)
5. Gut the cat (free)
6. Replace OEM muffler with Slip-on ($250-450)
7. Replace midpipe and headers (also removes cat) ($500?)

TIA!
 
I wouldn't do the air box mod or secondary flies without making sure the A/F ratio is correct which can be adjusted with a pc or tfi...Alot of owners have done it and haven't reported any problems...However, as far as I know it is yet to be seen what the A/F ratio actually looks like when doing these mods by themselves on the Bandit 1250...

Not the same bike but there have been some Dyno charts showing the A/F ratio on the ZX14 go to dangerously lean levels when doing the same mod (secondary fly removal) without FI adjustment....I would assume removal on the Bandit would have a similar leaning effect but to what extent that effect would be has not been shown for us to reference..Perhaps it's not enough to have any negative effect on engine longevity, but if it were me I wouldn't do the mod unless I knew for sure...
 
Thanks, Whitesands. There's a lot of discussion on other boards regarding pulling the secondaries (as well as a few other mods) with no other adjustments, but in my experience with changing airflow in carburated motors, there's always corresponding fuel adjustment that needs to occur.

I know that FI systems can handle some minor fluctuations in airflow, but some of these mods may push the sensors beyond their limits. There seems to be a lot of conflicting anecdotal information either way, but what you said makes a lot of sense, and with the lean condition these things come with from the factory, I don't want to take unnecesary risks.
 
One of the members on max suzuki and I think here( Rworm) did all the mods without an fi box or powercomander and had his bike dynoed. The AF ratios were all within spec and if I remember correctly his bike made 118hp and 90 something ft lbs of torque. Dale Walker also made a comment on removing the secondaries on the bandit vs the ZX14 and said while the overly lean issue was a concern for the Kawi it wasnt on the Bandit. Ive removed my secondaries, removed air box snorkel, gutted the cat, left the 02 sensor connected and have a scorpion slip on. Ive put on over 12k miles since doing these mods with no problems and the bike runs awsome, plugs look great and getting 50 mpg on the road. Not one person on any of the forums that I belong to has had any bad experiences with doing these free mods.
 
One of the members on max suzuki and I think here( Rworm) did all the mods without an fi box or powercomander and had his bike dynoed. The AF ratios were all within spec and if I remember correctly his bike made 118hp and 90 something ft lbs of torque. Dale Walker also made a comment on removing the secondaries on the bandit vs the ZX14 and said while the overly lean issue was a concern for the Kawi it wasnt on the Bandit. Ive removed my secondaries, removed air box snorkel, gutted the cat, left the 02 sensor connected and have a scorpion slip on. Ive put on over 12k miles since doing these mods with no problems and the bike runs awsome, plugs look great and getting 50 mpg on the road. Not one person on any of the forums that I belong to has had any bad experiences with doing these free mods.

Yes....Put mine on the dyno to check A/F and all was great....
0/2 bypassed with 1/2 watt 1k resistor....
Inner tubing pulled out of header.....Pods
 
I've been considering adding a TFI box for a while, and finally decided to do it this spring. My bike is running just fine as it is (Yosh can and air box modified), but I must admit that on hot days, stuck in traffic, I have been a little concerned about the engine running too lean and getting 'overly' hot because of it... I'm not sure if it is or not, but the TFI box will give me peace of mind, and squeeze a little more power out of the bike.

I would guess another great thing about the Dobeck TFI (and an advantage over the PC) is that the TFI box 'should' allow me to easily return the fueling settings back to stock by simply turning the pots back down to minimum - no need to disconnect it.
This is a great option to have; one could keep the stock setting when trying to achieve 'higher' fuel mileage (as when on a long trip), or bump up the fuel when a little extra torque and horse-power is required. I'm not sure if anyone has done this, but I don't see why it wouldn't work.
 
Just want to bring out some points....We have yet to see what the A/F ratio actually looks like with the mods done without the TFI...The only reference we have that can be seen is the stock pull Dale did on his dyno which showed the Bandit being very lean completely stock....If anything the Bandit looks like it needs some fuel richening bone stock at least at low rpm...

Look at the second chart down on Dales site....Stock Dyno pull shows it's already pretty lean...I just don't see the A/F ratio being fine with the secondaires being removed and an airbox breathing more air when it's already pretty lean to begin with...It goes from 17:1 at 2000 rpm and trends down to 15:1 at around 3,800 rpm....Looking at the chart kind of makes me want a TFI even without mods...Here's the link.

http://www.holeshot.com/
 
... the TFI box 'should' allow me to easily return the fueling settings back to stock by simply turning the pots back down to minimum - no need to disconnect it.

I just confirmed with Dobeck that resetting the three pots to '1' (lowest setting) will return the bike to stock mode. This of course completely defeats the purpose of having the TFI box, but it is an option - whatever the reason may be.

But I do agree that the Bandit, as many other bikes do, comes from the factory running as lean as 'safely' possible. I figure a little extra fuel is probably a good thing.
 
Since I'm not a wrench I must ask: what are the effects of running too lean? Why is it a problem?
 
Since I'm not a wrench I must ask: what are the effects of running too lean? Why is it a problem?

I think I remember reading something about the fact that gases produced during combustion form a lean mixture are much hotter than those from a rich mixture. I don't remember all the intricacies, but I think a richer mixture produces more carbon monoxide, which produces more pollution... hence the lean-running engines from the factory.
This should really not be a problem, until you start tinkering with the already-lean air/fuel mixture and adding more air-flow, this will cause the engine to run even hotter than it already is.

Please don't quote me on this, I'm sure someone out there will have a more accurate explanation.
 
Yes....Put mine on the dyno to check A/F and all was great....
0/2 bypassed with 1/2 watt 1k resistor....
Inner tubing pulled out of header.....Pods

Hey, rworm, Do you happen to have the sheets from the dyno pull to post up?
 
Since I'm not a wrench I must ask: what are the effects of running too lean? Why is it a problem?

Basically, running a lean mixture (more air than when in perfect tune) causes much hotter temperatures in the cylinders.

Here's a fairly good thread that discusses it:
http://hypography.com/forums/chemistry/3149-why-does-lean-engine-run-hot.html

The best way to tell if your engine is running too lean is to look at the spark plugs. If the mixture is too lean, they plugs will be covered with a white deposit. A proper Air/Fuel (A/F) mixture yields a more tan color to the plugs. Here's a good link for checking spark plug condition:

http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html
 
OK, I'm a noob when it comes to performance increases on FI engines. I'm also in the beginning stages of saving up to get the most I can out of the 1250 motor without replacing innards. Since it will be quite some time until I can afford to completely upgrade everything currently available, I'm trying to determine two main things:

1) Which of the "free" performance upgrades can be made before a TFI or PC is needed?
2) If operating on a budget, which performance upgrades provide the most bang for the buck, and what would be the proper order in performing them?

I plan to eventually upgrade my entire system, most likely with Dale Walker's complete Holeshot system, but if there's anything I can do in the meantime (i.e., free) until I save up the $$, I'd like to take care of it now.

Performance Mod (Cost)

1. Remove secondary butterflies (free)
2. Block/remove PAIR valve (free)
3. Modify air box cover (free)
4. (Is this where the TFI/PCIII is needed?)
5. Gut the cat (free)
6. Replace OEM muffler with Slip-on ($250-450)
7. Replace midpipe and headers (also removes cat) ($500?)

TIA!

I don't have a Bandit, however, a cheap change I have used on other bikes has been to simply go with one tooth less on the front sprocket. You lose about 8 percent of the top speed but better pull in the low and middle range of the power curve. On the negative side, it will impact the accuracy of your speedo reading.

Sprockets from Renthal cost about $35.00.

RB
 
1) Which of the "free" performance upgrades can be made before a TFI or PC is needed?
'Free' performance upgrades are about as readily available as "extra money".... f'getaboutit. Removal of the secondaries (seems to be) most effective when you start to mess'n around with intake & exhaust.

2) If operating on a budget, which performance upgrades provide the most bang for the buck, and what would be the proper order in performing them?
On a budget, and in order of 'best returns' (in my opinion):

1) A. Replace the OEM springs in yer tubes.
Factory springs are OVER-sprung, resulting in a rough riding front-end and difficulty in setting up a properly adjusted SAG. My budget did not allow me to pay for fancy/sexy Gold valving, so I'm happy with a good set of single-rate springs (progressive springs are better suited to simply cruising).
1) B. Fork brace..... I could NOT believe how much it improved my bike's stability and the ease with which it held a line when riding hard.

2) Replace the factory countersprocket with a 17 tooth.
The taller ratio factory sprocket helps with (more easlily) meeting EPA, noise standards, etc. in this 'lean' and "green" world. The bike is MUCH improved in day to day riding, freeway cruising, and short-shifting into traffic.

3) K&N air filter, one inch hole drilled in the air box lid, and removal of the snorkle.
Even with the factory muffler, improved air flow makes for a happier engine.
The fuel injection will take care of yer air/fuel ratio.

4) A cheap after-market muffler will LOOK cheap, but works none-the-less. But I favor a quality 17" Holeshot (Dale Walker) muffler WITH his DB reducer.
I found that my engine liked the added back pressure when I returned my (modified) DB killer to the end of my after-market can. When you get the TDI and a quality header system sans CAT', take that DB killer out and PARTY!

5) Replace the rear shock when you've logged 8,000 miles on it. A good shock absorber will be a GREAT marriage to that front-end you first upgraded. Some say shocks are good as long as they aren't leaking oil, but you WILL appreciate the smoother ride, and improved control of a suspension that works well.
 
3) K&N air filter, one inch hole drilled in the air box lid, and removal of the snorkle.
Even with the factory muffler, improved air flow makes for a happier engine.
The fuel injection will take care of yer air/fuel ratio.

I don't know if we can really count on the fuel injection to take care of its own air/fuel ratio. From what I understand air/fuel mixture on the Bandit is strictly monitored by the 'electronics' and always on the lean side. Kept stock (02 sensor connected and no TFI/PC) it will probably always try to lean itself out.
 
.... and it's for this reason that I followed through with Dale Walker's multiple runs on his Dyno, and his resulting settings for the TFI he offers. Can't beat peace of mind..... and not having to pay somebody to Dyno tune your bike for you.
 
Hey rworm how'd you get the inner tubing out of the header?


Cut em apart....
I disagree with alot of people on the forum....But dont post it....
Mine was runnin 14/7 AF across the board...Nobody wants to know any
tweeks me and my dyno man figured out w/o fuel adders;-)
From stock i gained the same HP (DIFFERENT DYNOS) as the best:trust:
I did have alot of runs and Eric is a busa tuner....He loved playin with the bike...

rworm

http://www.twtex.com/forums/showthread.php?t=36744&highlight=rworm
http://www.twtex.com/forums/showthread.php?t=39872&highlight=rworm
 
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