Are Dual Spark 1150's really better than Single Sparks re surging??

[John]

Gidday all,

 

I've been away from bikes for a couple of years due medical reasons. Prior to this I'd owned a couple of R1100RT's. They did exhibit varying levels of surging from time to time, but I found it easy to rectify through the usual procedures.

 

Now the time's come to get back into it, and I've been thinking of an 03-04 R1150RT. I've read through this forum extensively, and think I've got a pretty good handle on what to look out for in respect of mechanical problems.

 

Notwithstanding, what I haven't been able to ascertain is (with the evident failure rates and expense of replacing the stick coils on the dual spark) whether the dual spark is really that much better than the single, surge-wise?

 

Also, to those of you that own single spark 1150's - If your bike does surge, can it be reduced or eliminated in a similar way to the 1100's?

 

Any advice would be much appreciated.

[T__]

John, right out of the show room the twin spark version will have a noticeable lower amount of surge.. That is not to say the single sparker can’t be made to run fairly surge free..

 

I think a lot depends on how critical you are to surging & what speeds/gears you tend to ride in..

 

I have had other riders tell me how surge free their bikes are & when I ride them I can’t understand how they can say that..

 

I had an 02 single spark & although it took a fair amount of work it was actually better surge wise than my new 1200RT.. The single sparker can be made much better & in some cases quite surge free.. Basically to get the single sparker to be fairly surge free you will have to find a way to richen it up some & maybe play with the spark timing a little..

 

I guess it depends on how much effort you want to put into it & how critical you are to the surging issue..

 

The brakes seem to be better behaved on the later 1150RT’s also so that might be worth something by itself..

 

The later twin spark is probably a little better bike but you will pay more for it..

 

I was quite happy with my 02 1150RT but never did like the gear ratios as the 5th was too low & the 6th was too high.. Otherwise a nice bike with a good solid basic platform under it..

 

 

Twisty

 

[Gardner]

I just put a Techlusion on my 02 R1150RT two weeks ago and can't believe the difference. It surged and hunted at 3,500 which seems to be the speed I ride at a lot around town. I bought the 1150 about a year ago after several years on a K75RT so the surging was really noticeable after that smoothie. I lucked into the Techlusion for $75 used on the IBMWR site so figured I had nothing to lose. Easy to install, easy to tune, and knowing what I do now, would have gladly paid the $200+ for a new unit. I've never ridden an 1100 or dual spark but $200 is a cheap remidy for the 02-03 given the money you'll save by buying the older model. I'm leaving on a 4,000 mile rideabout next Saturday and feel like I'm on a new bike. I rode a 250 mile trip last week and didn't see much mileage drop but will be testing that more soon.

[JonathanE]

Seek and ye will find.

 

Seek not, and ye will find something else.

[DonW]

I've got 2 nearly identical bikes- a 2003 R1150RTP with Single spark, and a 2004 R1150RTP with dual spark. Both retired CHP bikes with 104K miles. Both serviced throughout their lives until I got them by good reputation BMW dealers. Both synched identically, by me. The 2003 surges at 3-4K rpm, and the 2004 doesn't. In some ways, the 2003 was smoother at high RPM than the 2004, but the surging drove me nuts. I need to consolidate the best of both bikes into one, and the 2003 lost the contest- it is now in parts in my garage- a big part of the decision was the surging.

 

Don

[John]

Thanks everybody for your responses so far. Please keep them coming.

 

Jon, I'm not quite sure what you meant in your reply. I'm but a simple Aussie. Could you please decode for me?

 

Regards.

[AndyS]

Thanks everybody for your responses so far. Please keep them coming.

 

Jon, I'm not quite sure what you meant in your reply. I'm but a simple Aussie. Could you please decode for me?

 

Regards.

 

My single spark surges, my twin spark doesn't (even when TBI is slightly out of sync).

 

The twin spark is newer and the brakes are better (better rear wheel bias).

 

If you can get it, go for the twin spark.

 

Andy

[rob1100r]

 

...but I found it easy to rectify through the usual procedures.

 

 

I'm on my second 1100, a 2000 (first was a '95). When cables are adjusted and t-bodys are synced using a mercury manometer as close as you can get them (I check at 2500 and 3500 bike warm of course, valves adjusted if needed). I have never had the surge, neither has my buddy with his 96...Just lucky I guess!

[smiller]

The surge is caused by occasional misfires (mixture not being ignited by the spark.) These occur in all engines but tend to be more noticeable in an engine with only two rather large-displacement cylinders. And the rather lean calibration due to emissions/cat converter only exacerbates the problem.

 

There a couple of things that can be done to help. Dual-spark is one (better chance of making sure a lean mixture gets lit off), or richen the mixture a bit (make the mixture easier to ignite in the first place.) The latter is off the table for BMW but not the owner, and a Techlusion or Power Commander can be (and usually are) quite effective.

 

Either method pretty much does the job. The dual-spark seems like a somewhat more elegant solution and is definitely desirable, depending on the premium you must pay for it of course. As to which of the two methods is more effective, hard to say...

[philbytx]

Here's my take...

 

I have a 2000 R1100R and a 2003 (2002 build) R1150RT.

I experience no surging on either....then again, I am anal about valve/TBS procedures.

 

IMHO, the dual spark adds an additional layer of complication and, thusly, "issues" with stick coil failures being one of them.

 

YMMV...

 

[tcausey]

I have a 2002 R1150RT and mine surges a little, but not bad. Valve adjustment and TBI sync and new plugs help. If you're real sensitive to it and it will drive you crazy, I'd go for the twin spark or other mods to the 02/03, but it is manageable if you're willing to work.

 

For me, it's a BMW, it's got character and quirks. If I wanted a bike without quirks and no soul I'd ride something else so I don't mind a little surging to be honest.

 

[ragtoplvr]

I have an 02 RS.

 

Use the Bosch 4418

 

Get a good sync and valve adjust.

 

I used to have a nice 454 powered Monte Carlo. It was warmed up just a bit. If any of you want to really experience surge, you should have driven that car. I Loved it. So, I do not mind what little surge the bike has. I just think of it as a bit too much overlap on the cam, and SMILE. Bike puts out much more HP per cubic inch than the old car. Then I twist my wrist, and smile much more.

 

Rod

 

[gmarktbone]

Mine has been much better since I installed Autolite 3923 plugs. The factory plugs were surging me all over the road. I don't have any experience with the twin spark or the 1100 to judge it against, but I can say that mine is not as bad with the cheap plugs.

[Mike O]

Here's my take...

 

I have a 2000 R1100R and a 2003 (2002 build) R1150RT.

I experience no surging on either....then again, I am anal about valve/TBS procedures.

 

IMHO, the dual spark adds an additional layer of complication and, thusly, "issues" with stick coil failures being one of them.

 

YMMV...

Ditto... 2003RT. Doesn't surge at all (unless TBS is way out of sync). I can deal with minor adjustments but would rather NOT deal with extra IMHO needed parts.

 

Mike O

[Boffin]

Here's my take...

 

I have a 2000 R1100R and a 2003 (2002 build) R1150RT.

I experience no surging on either....then again, I am anal about valve/TBS procedures.

 

IMHO, the dual spark adds an additional layer of complication and, thusly, "issues" with stick coil failures being one of them.

 

YMMV...

 

My '02 single spark RT surged slightly when under dealer servicing ( I just avoided that rev band), which was needed to keep within UK warranty requirements. My '04 twin-spark has never surged.

As to my mileage? That indeed did vary, with the twin-spark motor getting a consistent 10% better fuel consumption.

 

BTW, the move to twin-spark was to allow the big boxer to meet the then new Euro emissions regulations.

 

Andy

[ianboydsnr]

My 03 twinspark Gs has only ever surged, when one of the primary coils went faulty, my old 96 single spark 1100RT never surged, but my 2000 model 1100RT is surging quite badly, but it may just be the old fuel, as I have just got it and have yet to put any milage on it.

[Bill Dennes]

My '02 RT (9/01 build) used to be the King Of Surging. Wow!

 

Here's an oddball angle for you: Replace the left-side cam chain tensioner with the '04 version. That's what finally fixed my bike.

 

Here's a before-and-after comparison: Before I did the above fix, I bought the twin-spark setup from San Jose BMW. They made a second 14mm plug hole in each head and sold me a four-post coil and some extra plug wires. That was a good thing: It probably took 60% of the surge away.

 

I used a Techlusion 1030 before that, and gave it up because it always tuned the bike to stumble when it got rolling from a full stop.

 

Summary: I think that dual-spark models are smoother. I thank that some of the smoothness comes from the new cam-chain tensioner, which hit the market at the same time ('04). Thus, go for the '04.

[Bologna]

Let's go get that Monte Carlo!

[John]

Thanks a lot, folks, for the wisdom!

 

John.

[Rev. Jerry]

I had a 97 R1100RT and it surged so bad (what surge?) I traded it in for an 02 R1150RT. For the first 1000 or so miles it was smoother, but later developed a surge that was as bad as the 97. Dealers said "What surge?- don't ride in that rpm range" "That range" was from 2000 to 3500 rpms anytime I wasn't accelerating. Crusing got so bad my wife said she was done with riding, after hundreds of times hitting her helmet on mine. I traded it in july 03 for an 04 R1150RT and couldn't be happier. No surge, period at any speed or throttle position. They got it right, but it's a shame they only made it that one year. The 05's up are fine, but I still like the looks of the 04 better, so I'm keeping it. Mine started out getting 44mpg, but by the time it hit 20k, it gets 49-51 mpg all the time. I'm running synthetic fluids in it.

 

I spent several tries at the dealers trying to get rid of the surge that BMW said didn't exist, to no avail. So I decided to fix it myself. I used to work on VW Bosch Jetronic injection systems, so I had a few ideas how to fix it. If you have an older RT that surges, you may try changing the voltage reading at the left hand throttle body. My 02 surged at .029 volts very badly. That was the factory setting with paint installed on the screws. I adjusteded to .031 volts (richer, quicker tip-in)and it helped greatly, and thus eliminated the surge. Experimenting, I took it up as far as .035 volts, but it took longer to slow down, and mileage suffered (but more power). That may be a quick fix for you. the 02 got 44 mpg before I reset it on the average, and after resetting it to .031 it seemed to lose .3 mpg overall, not too bad a trade-off. However, wanting to keep the bike within "smog specs" I returned it to it's previous setting of .029 before deciding to trade it in for the 04.

[Dave in Doodah]

One more anecdotal data point for you. I have had the '03 single spark for a half year and 5k miles. There is a bit of a 'hunting' (would not call it surging) at low RPM in low gear (like in the neighborhood), but no surging that I can feel when in the 3-4K RPM cruising range at all. If I had hunting or surging at highway speeds, it would drive me nuts!

 

I am due for doing my first valve adjust and throttle body synch - coming up on 30K miles - so I am interested to see any changes in behavior.

[ianboydsnr]

One more anecdotal data point for you. I have had the '03 single spark for a half year and 5k miles. There is a bit of a 'hunting' (would not call it surging) at low RPM in low gear (like in the neighborhood), but no surging that I can feel when in the 3-4K RPM cruising range at all. If I had hunting or surging at highway speeds, it would drive me nuts!

 

I am due for doing my first valve adjust and throttle body synch - coming up on 30K miles - so I am interested to see any changes in behavior.

 

thats not hunting, thats stalling !