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SB8R - Hiccuping & Hesitation

 
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neil



Joined: 25 Apr 2016
Posts: 10
Location: Tucson (Arizona - USA)

PostPosted: Mon Apr 25, 2016 10:23 pm    Post subject: SB8R - Hiccuping & Hesitation Reply with quote

So, hopefully someone might have some ideas (or tell me it's normal) I just picked up an SB8R with 4000 ish miles.

Very nice bike, super clean & 1 owner. Took it out for the first time today (had to get it registered at the DMV).......it was struggling to tick over at first, but once warm was fine.

After about 40 miles it would hiccup & hesitate quite violently on part throttle when you roll on, if you open it up there isn't an issue.

It even did it at 6500rpm on part throttle. I opened it up a couple of times which seemed to clear it (idled ok & stopped hiccuping).
It's got a fuel trimmer on it, the PO said it was running great when he had it - and the trimmer shouldn't go below 400.

I've got a Ducati 996, that had similar symptoms a while ago - turned out the FI chip had taken a dump. But initially I'd changed the fuel filter, had the injectors cleaned - ended up Ducshop in ATL put it on his rollers & that was the issue.

So, I've read a little about the "stumble" on SB8's, but I assume that's not too violent - this was almost like the throttle was being closed and then opened again.

I think it's been sitting a while (with race gas in it), so I was really looking for pointers (I was thinking fuel filter & check the air filters & vacuum leaks, maybe injector cleaning) - but the PO mentioned there isn't a fuel filter.......so I'm just wondering if anyone had come across this before.

I'm originally from Newcastle (UK) - and M&S were both Bimota and Ducati dealers in the '00's, so I've finally got the two bikes I drooled over back in the day!

Thanks

Neil
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waggy



Joined: 26 Sep 2011
Posts: 277
Location: Northern Ireland

PostPosted: Tue Apr 26, 2016 12:51 pm    Post subject: Reply with quote

Hi Neil,

Congrats on your sb8r, they are a great bike. I have no experience of fuel trimmer as mine use power commander. Its quite normal for them not to idle properly till they warm up, but they should not hesitate as you describe. Its quite a low mileage so has been probably stood a long time, best check simple things first. The air filter can dry out and crumble a bit so make sure its in good nick and oiled. There is a fuel filter in the tank which you should replace..its visible in parts manual.

http://www.sfogliami.it/flip.asp?sc=an1qr8ga3pxoxh3nlny6xgs8fairppc5&ID=117617#page/47

Check fuel hose condition, spark plugs etc also clean and check any electrical and earth connections. Hopefully you will be running good in no time.
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neil



Joined: 25 Apr 2016
Posts: 10
Location: Tucson (Arizona - USA)

PostPosted: Tue Apr 26, 2016 6:03 pm    Post subject: Reply with quote

Thanks - I'll give it a go!

On the subject of the PC, I know they're not plug & play on these.....I've got one on the 996, and wondered if you had any other info you could share?

I'd read somewhere they were a Triumph PC3? Would you happen to have a copy of the base tune you could share?

I was surprised with the SB8, I was expecting it to be like the 996 to ride, but honestly it's like night & day.

Looking forward to getting it running correctly - also from my browsing I'd seen a few posts on the TPS, probably give that a clean whilst I'm in there!

Thanks again!

Neil
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waggy



Joined: 26 Sep 2011
Posts: 277
Location: Northern Ireland

PostPosted: Tue Apr 26, 2016 9:07 pm    Post subject: Reply with quote

My SB8r's both had pc3's fitted by previous owners, who had them installed and set up on dyno by Chris Gunster Dynojet centre, Grimsby +44 1472251222.
Some time ago l enquired on behalf of a chap from spain who had an sb8r what was invovled. Chris Gunster said that they use and adapt a triumph pc3, they have quite a bit of experience in fitting pc3 to sb8r's and were happy to make up a kit, with correct cables, maps etc and ship to anywhere. Might be worth contacting them if you need to go down the pc3 route. But reckon a good service and clean is probably all you need, in tank fuel filters often get ignored but could solve your problems, am always the optimist Very Happy

Also had a duc 966, definitely chalk and cheese.
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wdm



Joined: 02 Sep 2012
Posts: 14
Location: Connecticut, USA

PostPosted: Sun May 01, 2016 6:49 pm    Post subject: Reply with quote

Hi Neil - Look at this thread. Follow the link inside it for TPS cleaning instructions.
http://www.bimotaforum.co.uk/viewtopic.php?t=4472
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neil



Joined: 25 Apr 2016
Posts: 10
Location: Tucson (Arizona - USA)

PostPosted: Mon May 02, 2016 3:43 am    Post subject: Reply with quote

wdm wrote:
Hi Neil - Look at this thread. Follow the link inside it for TPS cleaning instructions.
http://www.bimotaforum.co.uk/viewtopic.php?t=4472


Thanks! If come across that thread & thought that may be an issue.

I pulled the tank off it one night last week, the PO must've had issues with the quick disconnects on the fuel lines & had replaced them with some alloy versions & hose clips.....whilst not terrible I didn't like it. Sooooo, I ended up ordering some stainless hose from belmetric with crimp on connectors to replace it.
Long story short I'm going to replace the hoses - but I also thought it better to replace with factory - so I ordered a new set (I'll make the stainless ones up anyway).....

Anyway, when I was in there I cleaned the TPS, and pulled the pump out too (again, nothing untoward)....suction filter & post filter seem fine. I figured I may as well replace them when I'm in there. Whilst they're not available from bimota the pump is a walbro - so the suction filter is (fingers crossed as it hasn't arrived yet) readily available. The plastic post pump filter I was going to substitute with a Wix FI filter.

Hopefully I'll get the gaskets & lines from Bimota Classic tomorrow as well as the shop manual I ordered so fingers crossed I'll have it back together mid week.....hopefully the shop manual has the procedure for setting the throttle bodies too as I thought I may as well do that too.

Thanks for the input though - much appreciated!

Neil
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atomibart



Joined: 11 Apr 2011
Posts: 120
Location: France

PostPosted: Mon May 09, 2016 4:32 pm    Post subject: Reply with quote

How does the power commander work ? Is it still possible to find one of these ?

atomibart
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waggy



Joined: 26 Sep 2011
Posts: 277
Location: Northern Ireland

PostPosted: Tue May 10, 2016 1:25 pm    Post subject: Reply with quote

atomibart wrote:
How does the power commander work ? Is it still possible to find one of these ?

atomibart


Basically the power commander is a plug in box of electronics thats inline with the bikes ecu. The PC3 lets you adjust the fuel/air ratio throughout the entire rev range. A standard bike ecu has to comply with eu emissions which is always a bit of a compromise with optimal engine performance. A PC3 will allow you to fine tune the engine for optimal performance, for example if you changed your exhaust and airfilter for more free flowing items, your standard ecu would not recognise this and would continue to use its standard map. The PC3 allows you to make a custom map, best suited to your bikes specification, preferably set up on a dyno. Hope that makes sense

See my previous post above as to where to get one.
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atomibart



Joined: 11 Apr 2011
Posts: 120
Location: France

PostPosted: Tue May 10, 2016 2:38 pm    Post subject: Reply with quote

Thank you very much waggy

Maybe you could also answer to a question I posted in another thread :

"I am French and not so familiar with english technical words so could someone explain again to me what TB is and where the TPS is located?
I am experiencing this 'hiccuping & hesitation' problem with my SB8RS now...last winter I cleaned the air filter, changed the spark plugs and some crackled hoses, had the injectors cleaned in ultrasound bath...and for my first ride of the year I encountered this problem when opening the throttle."

atomibart
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waggy



Joined: 26 Sep 2011
Posts: 277
Location: Northern Ireland

PostPosted: Tue May 10, 2016 4:03 pm    Post subject: Reply with quote

TB stands for throttle body which you can see here on parts book tav10

http://www.sfogliami.it/flip.asp?sc=an1qr8ga3pxoxh3nlny6xgs8fairppc5&ID=117617#page/21

TPS stands for throttle position sensor and is part 4 potentiometer. If you need to remove tps, be sure to scribe a fine mark on both to ensure its put back to same position. They can be sensitive, might you have accidently knocked it when you cleaned your injectors.
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neil



Joined: 25 Apr 2016
Posts: 10
Location: Tucson (Arizona - USA)

PostPosted: Sun May 15, 2016 11:27 pm    Post subject: Reply with quote

So, just to close this one out.....I noticed that the previous owner had replaced the quick disconnects on the fuel line with some aluminum versions & jubilee clips into the ptfe fuel lines.

So, I ordered a set & sender unit gasket from Bimota Classic Spares...got them fitted yesterday - and additionally replaced the suction filter (walbro 125-135b for those interested) and also the post pump filter (used a wix 33032).....cleaned the tps, cleaned & oiled the air filter......fought the banjo fittings to stop them leaking (even with new crush washers - all good now).

Also, peering down into the battery - noticed an earth lead dangling! Guess the PO missed that when he changed the battery! No idea where it goes to, but put it back on.

It's like night & day - no hesitation, stumbling......pulls hard from low revs - really how I thought it would be!

I'd suspect it was the TPS, but perhaps the dangling earth may have been something to do with it. Anyway, all good in the word again!
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